CVE-2025-40135VulnerabilityPublished 4 Jun 2026Updated 1 Nov 2026

Red Hat Security Advisory: kernel security update

Affects Linux kernelSource GCVE Database

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Mentioned vulnerabilities

Authoritative record:CVE-2025-40135· High 8.1

Not known to be exploited · CVSS 8.1 High · fixed in Red Hat package updates : patch Linux kernel soon.

Data as of 1 Nov 2026, 08:20 UTC

CVSS 3.1 base score

8.1High

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (Linux)	CVSS 3.1	8.1

EPSS: 0.7% chance of exploitation in 30 days – higher than 53% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f69fec6287565fdeb61f65e700a1184352306943, f7f9e924f23684b4b23cd9f976cceab24a968e34, f0a54d00d2f36de40266f47c27989853e8588656 +3

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

Attack Vector: Network
Attack Complexity: High
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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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 12 Nov 2025
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 31 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.

ghsa-q28q-889g-6rx2

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, < f69fec6287565fdeb61f65e700a1184352306943	Fixed in f69fec6287565fdeb61f65e700a1184352306943
LinuxLinux	Affected ≥ 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, < f7f9e924f23684b4b23cd9f976cceab24a968e34	Fixed in f7f9e924f23684b4b23cd9f976cceab24a968e34
LinuxLinux	Affected ≥ 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, < f0a54d00d2f36de40266f47c27989853e8588656	Fixed in f0a54d00d2f36de40266f47c27989853e8588656
LinuxLinux	Affected ≥ 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, < bd0905e2122e3680968cd0741966983490bf2ed3	Fixed in bd0905e2122e3680968cd0741966983490bf2ed3
LinuxLinux	Affected ≥ 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, < 9085e56501d93af9f2d7bd16f7fcfacdde47b99c	Fixed in 9085e56501d93af9f2d7bd16f7fcfacdde47b99c
LinuxLinux	Affected ≥ 4a6ce2b6f2ecabbddcfe47e7cf61dd0f00b10e36, < 7a228cfbb66cca49e9baf901c506364f8dfe036b	Fixed in 7a228cfbb66cca49e9baf901c506364f8dfe036b

AI-suggested

Red Hat has released updated kernel and kernel-rt packages for affected Red Hat Enterprise Linux versions 9.2 and 9.4 that address these vulnerabilities. Users should apply these official updates promptly and reboot their systems to ensure the fixes take effect. For detailed update instructions, refer to Red Hat's official advisory and knowledge base article at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the vendor-provided patches and rebooting.

Description

The kernel packages contain the Linux kernel, the core of any Linux operating system. Security Fix(es): * kernel: net: use dst_dev_rcu() in sk_setup_caps() (CVE-2025-40170) * kernel: ipv6: use RCU in ip6_xmit() (CVE-2025-40135) * kernel: ipv6: use RCU in ip6_output() (CVE-2025-40158) * kernel: crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id (CVE-2025-68724) * kernel: iommu: disable SVA when CONFIG_X86 is set (CVE-2025-71089) * kernel: scsi: target: iscsi: Fix use-after-free in iscsit_dec_conn_usage_count() (CVE-2026-23216) * kernel: netfilter: nf_tables: release flowtable after rcu grace period on error (CVE-2026-23392) * kernel: netfilter: ip6t_eui64: reject invalid MAC header for all packets (CVE-2026-31685) * kernel: ip6_tunnel: clear skb2->cb[] in ip4ip6_err() (CVE-2026-43037) * kernel: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() (CVE-2026-43038) * kernel: smb: client: validate the whole DACL before rewriting it in cifsacl (CVE-2026-31709) * kernel: wifi: brcmfmac: validate bsscfg indices in IF events (CVE-2026-43110) 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 collectively pose a high security impact as rated by Red Hat. They could potentially allow attackers to cause system instability, denial of service, or unauthorized access to kernel-level operations. Specific impacts include use-after-free leading to memory corruption, overflow conditions in cryptographic key generation, improper packet handling in IPv6 and netfilter subsystems, and validation bypasses in SMB client access control. However, there are no known exploits in the wild reported at this time.

Summary

This Red Hat security advisory addresses numerous vulnerabilities in the Linux kernel and kernel-rt packages for Red Hat Enterprise Linux versions 9.2 and 9.4. The vulnerabilities include CVE-2025-40135, CVE-2025-40158, CVE-2025-40170, CVE-2025-68724, CVE-2025-71089, CVE-2026-23216, CVE-2026-23392, CVE-2026-31685, CVE-2026-43037, CVE-2026-43038, CVE-2026-46243, and others. These issues involve improper use of Read-Copy-Update (RCU) mechanisms, use-after-free bugs, overflow conditions, and validation errors in kernel networking, cryptographic key generation, IOMMU configuration, SCSI target handling, netfilter flowtable management, IPv6 packet processing, SMB client access control, and wireless driver event handling. The advisory provides updated kernel packages that fix these vulnerabilities, requiring a reboot to apply the changes.

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-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-190Integer Overflow or Wraparound (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Requirements
Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
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.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.3 (opens in a new tab)
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-820Missing Synchronization (opens in a new tab)
Base weakness
The product utilizes a shared resource in a concurrent manner but does not attempt to synchronize access to the resource.
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-1287Improper Validation of Specified Type of Input (opens in a new tab)
Base weakness
The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type.
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-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-843Access of Resource Using Incompatible Type (Type Confusion) (opens in a new tab)
Base weakness
The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.
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-911Improper Update of Reference Count (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product uses a reference count to manage a resource, but it does not update or incorrectly updates the reference count.
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-617Reachable Assertion (opens in a new tab)
Base weakness
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
Implementation
If the assertion statement is required (e.g., for security or reliability), change the invoking code to avoid the conditions that trigger the assertion.
Implementation
Consider changing the assertion to some other less "fatal" error. This might not be easy to implement, since other code may be needed to handle the error.
Implementation
Make sensitive open/close operations non-reachable from directly user-controlled data (e.g. open/close resources)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-909Missing Initialization of Resource (opens in a new tab)
Class weaknessLikelihood of exploit: Medium
The product does not initialize a critical resource.
Implementation
Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all specified steps.
Implementation
Pay close attention to complex conditionals that affect initialization, since some branches might not perform the initialization.
Implementation
Avoid race conditions (CWE-362) during initialization routines.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.
Implementation
The most basic advice for TOCTOU vulnerabilities is to not perform a check before the use. This does not resolve the underlying issue of the execution of a function on a resource whose state and identity cannot be assured, but it does help to limit the false sense of security given by the check.
Implementation
When the file being altered is owned by the current user and group, set the effective gid and uid to that of the current user and group when executing this statement.
Architecture and Design
Limit the interleaving of operations on files from multiple processes.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V1.11.3 (opens in a new tab)
V11.1.6 (opens in a new tab)
V1.11.2 (opens in a new tab)
Attack patterns
Leveraging Race Conditions via Symbolic Links (opens in a new tab)
Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Aug 2026, 20:35 UTC

WeaknessesCWE-825, CWE-416, CWE-190 +11

Technical details

References

Community reviews

Related threats