VulnerabilityPublished 25 Apr 2026Updated 19 Oct 2026

CVE-2026-31682: Linux kernel · bridge: br_nd_send: linearize skb before parsing ND options

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 9.1 Critical · fixed in c68433fd291c9e88c00292095172c62d1997d662 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 14:18 UTC

CVSS 3.1 base score

9.1Critical

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

EPSS

0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers can reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch

Available – fixed in c68433fd291c9e88c00292095172c62d1997d662, bd91ec85aa4c77d645bd2739fc56784157a88ca2, a01aee7cafc575bb82f5529e8734e7052f9b16ea +5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
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: None: There is no loss of integrity within 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 25 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 ≥ ed842faeb2bd49256f00485402f3113205f91d30, < c68433fd291c9e88c00292095172c62d1997d662	Fixed in c68433fd291c9e88c00292095172c62d1997d662
LinuxLinux	Affected ≥ ed842faeb2bd49256f00485402f3113205f91d30, < bd91ec85aa4c77d645bd2739fc56784157a88ca2	Fixed in bd91ec85aa4c77d645bd2739fc56784157a88ca2
LinuxLinux	Affected ≥ ed842faeb2bd49256f00485402f3113205f91d30, < a01aee7cafc575bb82f5529e8734e7052f9b16ea	Fixed in a01aee7cafc575bb82f5529e8734e7052f9b16ea
LinuxLinux	Affected ≥ ed842faeb2bd49256f00485402f3113205f91d30, < 658261898130da620fc3d0fbb0523efb3366cb55	Fixed in 658261898130da620fc3d0fbb0523efb3366cb55
LinuxLinux	Affected ≥ ed842faeb2bd49256f00485402f3113205f91d30, < 9c55e41c73af5c4511070933b1bd25248521270c	Fixed in 9c55e41c73af5c4511070933b1bd25248521270c
LinuxLinux	Affected ≥ ed842faeb2bd49256f00485402f3113205f91d30, < 4f397b950c916e9a1f8a4fce04ea0110206cad47	Fixed in 4f397b950c916e9a1f8a4fce04ea0110206cad47

AI-suggested

A fix is available and has been applied in several Linux kernel commits. Users and administrators should update their Linux kernel to a fixed version that includes these patches. Since this is not a cloud service, manual patching is required. There are no vendor advisories indicating no action is needed or that mitigation is automatic.

Description

CVE-2026-31682 is a critical vulnerability in the Linux kernel's bridge component where the function br_nd_send() improperly handles neighbor discovery options. The function assumes these options are in a linear buffer, but callers only guarantee linearity of the ICMPv6 header and target address, potentially causing out-of-bounds memory access. This flaw has been fixed by ensuring the request is linearized before parsing the options.

Impact

This vulnerability allows an unauthenticated remote attacker to cause a buffer over-read in the Linux kernel's network stack by sending specially crafted ICMPv6 neighbor discovery packets. The CVSS 3.1 score is 9.1 (critical) with network attack vector, low attack complexity, no privileges required, no user interaction, and impacts confidentiality and availability. Exploitation could lead to kernel memory disclosure and denial of service via system crash.

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).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 13:37 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

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