CVE-2026-23270VulnerabilityPublished 4 May 2026Updated 16 Oct 2026

Red Hat Security Advisory: kernel security update

Affects Linux kernelSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-23270· High 7.8

Not known to be exploited · CVSS 7.8 High · fixed in Red Hat package updates : patch Linux kernel soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score

7.8High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in fb3c380a54e33d1fd272cc342faa906d787d7ef1, bc4e5bb529823a09f02dbe96169de679a9db26e0, 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e +8

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=5.15.148 <5.15.203 >=6.1.75 <6.1.167 >=6.6.14 <6.6.130 >=6.7.2 <6.8	Fixed in fb3c380a54e33d1fd272cc342faa906d787d7ef1 bc4e5bb529823a09f02dbe96169de679a9db26e0 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e 380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6 11cb63b0d1a0685e0831ae3c77223e002ef18189 9deda0fcda5c1f388c5e279541850b71a2ccfcf4 6.8 6.6.130 6.1.167 5a110ddcc99bda77a28598b3555fe009eaab3828 5.15.203
LinuxLinux	Affected =6.8	Fixed in–

AI-suggested

Red Hat has released an official kernel update for Red Hat Enterprise Linux 8.8 that addresses these vulnerabilities. Users should apply the update promptly following Red Hat's guidance at https://access.redhat.com/articles/11258 and reboot affected systems to ensure the fixes take effect. No additional mitigation steps are required beyond applying the official patch and rebooting.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix(es): * kernel: Linux kernel: Use-after-free in traffic control (act_ct) may lead to denial of service or privilege escalation (CVE-2026-23270) * kernel: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() (CVE-2026-23455) * kernel: mptcp: fix slab-use-after-free in __inet_lookup_established (CVE-2026-31669) * kernel: ALSA: usb-audio: Add sanity check for OOB writes at silencing (CVE-2026-43279) * kernel: tcp: fix potential race in tcp_v6_syn_recv_sock() (CVE-2026-43198) * kernel: dlm: validate length in dlm_search_rsb_tree (CVE-2026-43125) * kernel: netfilter: flowtable: strictly check for maximum number of actions (CVE-2026-43329) * kernel: ALSA: aloop: Fix peer runtime UAF during format-change stop (CVE-2026-46090) * kernel: RDMA/rxe: Fix double free in rxe_srq_from_init (CVE-2026-45852) * kernel: RDMA/mlx4: Fix mis-use of RCU in mlx4_srq_event() (CVE-2026-46181) Bug Fix(es) and Enhancement(s): * NVMe-FC: Panic during NVMe Controller Reset tests (JIRA:RHEL-178449) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Impact

The vulnerabilities fixed in this advisory affect the Linux kernel core of Red Hat Enterprise Linux 8.8, potentially allowing denial of service or privilege escalation attacks via use-after-free and other memory corruption issues. The impact includes possible system crashes, unauthorized privilege gains, and instability in kernel subsystems such as networking, audio, and RDMA. The update mitigates these risks by correcting memory handling, input validation, and race conditions in affected kernel components.

Summary

This Red Hat security advisory (RHSA-2026:35863) details an important update to the Linux kernel packages in Red Hat Enterprise Linux 8.8 addressing multiple security vulnerabilities. The key security fixes include a use-after-free vulnerability in the traffic control act_ct module (CVE-2026-23270) that could allow denial of service or privilege escalation. Additional vulnerabilities fixed involve zero-length checks in netfilter's nf_conntrack_h323 (CVE-2026-23455), slab-use-after-free in multipath TCP (__inet_lookup_established, CVE-2026-31669), out-of-bounds write checks in ALSA USB audio (CVE-2026-43279), race conditions in TCP IPv6 SYN receive socket (CVE-2026-43198), length validation in distributed lock manager (CVE-2026-43125), maximum action checks in netfilter flowtable (CVE-2026-43329), use-after-free in ALSA aloop (CVE-2026-46090), double free in RDMA rxe_srq_from_init (CVE-2026-45852), and misuse of RCU in RDMA mlx4_srq_event (CVE-2026-46181). The advisory also includes bug fixes and enhancements such as preventing panics during NVMe controller reset tests. The update requires a system reboot to apply the fixes. The advisory references multiple CVEs and provides links to Red Hat's errata and update instructions.

CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-763Release of Invalid Pointer or Reference (opens in a new tab)
Base weakness
The product attempts to return a memory resource to the system, but it calls the wrong release function or calls the appropriate release function incorrectly.
Implementation
Only call matching memory management functions. Do not mix and match routines. For example, when you allocate a buffer with malloc(), dispose of the original pointer with free().
Implementation
When programming in C++, consider using smart pointers provided by the boost library to help correctly and consistently manage memory.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-130Improper Handling of Length Parameter Inconsistency (opens in a new tab)
Base weakness
The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.
Implementation
When processing structured incoming data containing a size field followed by raw data, ensure that you identify and resolve any inconsistencies between the size field and the actual size of the data.
Implementation
Do not let the user control the size of the buffer.
Implementation
Validate that the length of the user-supplied data is consistent with the buffer size.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Buffer Overflow via Parameter Expansion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-821Incorrect Synchronization (opens in a new tab)
Base weakness
The product utilizes a shared resource in a concurrent manner, but it does not correctly synchronize access to the resource.
CWE-787Out-of-bounds Write (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #5
The product writes data past the end, or before the beginning, of the intended buffer.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-770Allocation of Resources Without Limits or Throttling (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #25
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Requirements
Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Architecture and Design
Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
Architecture and Design
Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V8.1.4 (opens in a new tab)
V13.4.1 (opens in a new tab)
V11.1.4 (opens in a new tab)
Attack patterns
XML Ping of the Death (opens in a new tab)
Exponential Data Expansion (opens in a new tab)
Serialized Data Parameter Blowup (opens in a new tab)
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-364Signal Handler Race Condition (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product uses a signal handler that introduces a race condition.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design
Design signal handlers to only set flags, rather than perform complex functionality. These flags can then be checked and acted upon within the main program loop.
Implementation
Only use reentrant functions within signal handlers. Also, use validation to ensure that state is consistent while performing asynchronous actions that affect the state of execution.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.2 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-366Race Condition within a Thread (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
If two threads of execution use a resource simultaneously, there exists the possibility that resources may be used while invalid, in turn making the state of execution undefined.
Architecture and Design
Use locking functionality. This is the recommended solution. Implement some form of locking mechanism around code which alters or reads persistent data in a multithreaded environment.
Architecture and Design
Create resource-locking validation checks. If no inherent locking mechanisms exist, use flags and signals to enforce your own blocking scheme when resources are being used by other threads of execution.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
Leveraging Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1288Improper Validation of Consistency within Input (opens in a new tab)
Base weakness
The product receives a complex input with multiple elements or fields that must be consistent with each other, but it does not validate or incorrectly validates that the input is actually consistent.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-131Incorrect Calculation of Buffer Size (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product does not correctly calculate the size to be used when allocating a buffer.
Implementation
When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts "&" characters to "&" for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input…
Implementation
Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, "not-a-number" calculations, and how the language handles…
Implementation · Input Validation
Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.
Attack patterns
Overflow Buffers (opens in a new tab)
Buffer Overflow via Parameter Expansion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-1341Multiple Releases of Same Resource or Handle (opens in a new tab)
Base weakness
The product attempts to close or release a resource or handle more than once, without any successful open between the close operations.
Implementation
Change the code's logic so that the resource is only closed once. This might require simplifying or refactoring. This fix can be simple to do in small code blocks, but more difficult when multiple closes are buried within complex conditionals.
Implementation · Refactoring
It can be effective to implement a flag that is (1) set when the resource is opened, (2) cleared when it is closed, and (3) checked before closing. This approach can be useful when there are disparate cases in which closes must be performed.
Implementation · Refactoring
When closing a resource, set the resource's associated variable to NULL or equivalent value for the given language. Some APIs will ignore this null value without causing errors.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Jul 2026, 15:03 UTC

WeaknessesCWE-416, CWE-125, CWE-763 +9

Technical details

References

Community reviews

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