CVE-2026-31669VulnerabilityPublished 16 Jun 2026Updated 30 Oct 2026

Red Hat Security Advisory: kernel security update

Affects Linux kernelSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2026-31669· Critical 9.8

Not known to be exploited · CVSS 9.8 Critical · fixed in Red Hat package updates : patch Linux kernel as a priority.

Data as of 30 Oct 2026, 20:25 UTC

CVSS 3.1 base score

9.8Critical

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in fb1f54b7d16f393b8b65d328410f78b4beea8fcc, f6e1f25fa5e733570f6d6fe37a4dfed2a0deba47, eb9c6aeb512f877cf397deb1e4526f646c70e4a7 +4

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
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: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
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 24 Apr 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 30 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 ≥ b19bc2945b40b9fd38e835700907ffe8534ef0de, < fb1f54b7d16f393b8b65d328410f78b4beea8fcc	Fixed in fb1f54b7d16f393b8b65d328410f78b4beea8fcc
LinuxLinux	Affected ≥ b19bc2945b40b9fd38e835700907ffe8534ef0de, < f6e1f25fa5e733570f6d6fe37a4dfed2a0deba47	Fixed in f6e1f25fa5e733570f6d6fe37a4dfed2a0deba47
LinuxLinux	Affected ≥ b19bc2945b40b9fd38e835700907ffe8534ef0de, < eb9c6aeb512f877cf397deb1e4526f646c70e4a7	Fixed in eb9c6aeb512f877cf397deb1e4526f646c70e4a7
LinuxLinux	Affected ≥ b19bc2945b40b9fd38e835700907ffe8534ef0de, < b313e9037d98c13938740e5ebda7852929366dff	Fixed in b313e9037d98c13938740e5ebda7852929366dff
LinuxLinux	Affected ≥ b19bc2945b40b9fd38e835700907ffe8534ef0de, < 15fa9ead4d5e6b6b9c794e84144146c917f2cb62	Fixed in 15fa9ead4d5e6b6b9c794e84144146c917f2cb62
LinuxLinux	Affected ≥ b19bc2945b40b9fd38e835700907ffe8534ef0de, < 9b55b253907e7431210483519c5ad711a37dafa1	Fixed in 9b55b253907e7431210483519c5ad711a37dafa1

AI-suggested

Red Hat has released updated kernel and kernel-rt packages that address these vulnerabilities. Users should apply the provided security updates promptly and reboot affected systems to ensure the fixes take effect. Detailed update instructions are available in the Red Hat advisory. There are no indications that additional mitigations beyond applying the official patches and rebooting are required.

Description

The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements. Security Fix(es): * kernel: mptcp: fix slab-use-after-free in __inet_lookup_established (CVE-2026-31669) * kernel: xen/privcmd: fix double free via VMA splitting (CVE-2026-31787) * kernel: Buffer overflow in drivers/xen/sys-hypervisor.c (CVE-2026-31786) * kernel: wifi: brcmfmac: validate bsscfg indices in IF events (CVE-2026-43110) * kernel: netfilter: flowtable: strictly check for maximum number of actions (CVE-2026-43329) * kernel: Bluetooth: hci_event: fix potential UAF in SSP passkey handlers (CVE-2026-46056) * kernel: wifi: mac80211: drop stray 'static' from fast-RX rx_result (CVE-2026-46152) * kernel: wifi: mac80211: remove station if connection prep fails (CVE-2026-46125) 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 include memory corruption issues such as use-after-free and double free, buffer overflow, and improper validation that could lead to system instability or potential privilege escalation. The security impact is rated as important by Red Hat, indicating these issues could be exploited to compromise system integrity or availability if left unpatched. No known exploits in the wild have been reported at this time.

Summary

This Red Hat security advisory covers a kernel update for Red Hat Enterprise Linux 8 that fixes several vulnerabilities: a slab-use-after-free in the mptcp component (__inet_lookup_established) (CVE-2026-31669), a double free via VMA splitting in xen/privcmd (CVE-2026-31787), a buffer overflow in drivers/xen/sys-hypervisor.c (CVE-2026-31786), validation issues in wifi brcmfmac bsscfg indices (CVE-2026-43110), strict checking of maximum actions in netfilter flowtable (CVE-2026-43329), a potential use-after-free in Bluetooth SSP passkey handlers (CVE-2026-46056), and fixes in wifi mac80211 components (CVE-2026-46125, CVE-2026-46152). The advisory provides updated packages and requires rebooting the system for the fixes to apply.

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-170Improper Null Termination (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product does not terminate or incorrectly terminates a string or array with a null character or equivalent terminator.
Requirements
Use a language that is not susceptible to these issues. However, be careful of null byte interaction errors (CWE-626) with lower-level constructs that may be written in a language that is susceptible.
Implementation
Ensure that all string functions used are understood fully as to how they append null characters. Also, be wary of off-by-one errors when appending nulls to the end of strings.
Implementation
If performance constraints permit, special code can be added that validates null-termination of string buffers, this is a rather naive and error-prone solution.
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-1285Improper Validation of Specified Index, Position, or Offset in Input (opens in a new tab)
Base weakness
The product receives input that is expected to specify an index, position, or offset into an indexable resource such as a buffer or file, but it does not validate or incorrectly validates that the specified index/position/offset has the required properties.
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-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-413Improper Resource Locking (opens in a new tab)
Base weakness
The product must have exclusive access to a resource, but it does not lock or does not correctly lock that resource.
Architecture and Design
Use a non-conflicting privilege scheme.
Architecture and Design · Implementation
Use synchronization when locking a resource.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-825Expired Pointer Dereference (opens in a new tab)
Base weakness
The product dereferences a pointer that contains a location for memory that was previously valid, but is no longer valid.
Architecture and Design
Choose a language that provides automatic memory management.
Implementation
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-1058Invokable Control Element in Multi-Thread Context with non-Final Static Storable or Member Element (opens in a new tab)
Base weakness
The code contains a function or method that operates in a multi-threaded environment but owns an unsafe non-final static storable or member data element.

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Aug 2026, 00:06 UTC

WeaknessesCWE-763, CWE-170, CWE-1285 +4

Technical details

References

Community reviews

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