VulnerabilityPublished 4 Sep 2026Updated 6 Nov 2026

CVE-2026-80844: Linux kernel · xfrm: ah6: validate routing header segments_left

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f00df8500e5a36ba70d336fd34bd2152ea074e5f : patch Linux kernel soon.

Data as of 6 Nov 2026, 17:34 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch

Available – fixed in f00df8500e5a36ba70d336fd34bd2152ea074e5f, 46640c814f25f096b0b0045ca50e1b7030cd8a30, 6733ae71268a27d598cfb3f3339a3c950b9b656d +6

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Sep 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 6 Nov 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 ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < f00df8500e5a36ba70d336fd34bd2152ea074e5f	Fixed in f00df8500e5a36ba70d336fd34bd2152ea074e5f
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 46640c814f25f096b0b0045ca50e1b7030cd8a30	Fixed in 46640c814f25f096b0b0045ca50e1b7030cd8a30
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 6733ae71268a27d598cfb3f3339a3c950b9b656d	Fixed in 6733ae71268a27d598cfb3f3339a3c950b9b656d
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 1516e31ac458a738be485620579d8f7fb2700fcb	Fixed in 1516e31ac458a738be485620579d8f7fb2700fcb
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 48b0e36cf54358276ee7aa897034c973097d2bc9	Fixed in 48b0e36cf54358276ee7aa897034c973097d2bc9
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 7bad4bda74dc4713f398d3b7624ff05478e3a568	Fixed in 7bad4bda74dc4713f398d3b7624ff05478e3a568

AI-suggested

A fix has been implemented in the Linux kernel source code as indicated by multiple fixed commit versions. Users and administrators should update their Linux kernel to a version that includes these fixes. Since this is not a cloud service, manual patching is required. There are no vendor advisories stating no action is needed or that the issue is already mitigated without patching.

Description

A vulnerability in the Linux kernel's IPv6 AH6 implementation allows out-of-bounds memory access due to improper validation of the routing header's segments_left field. The flaw arises when segments_left exceeds the number of addresses indicated by the hdrlen field, leading to unsafe memory operations. This issue has been fixed by validating segments_left before modifying the routing header or performing pointer arithmetic.

Reports on CVE-2026-80844

ZDI-26-834: Linux Kernel IPv6 AH Routing Header Integer Underflow Local Privilege Escalation VulnerabilityZero Day Initiative2026-10-29

Impact

The vulnerability can lead to out-of-bounds memory access in kernel space, which may cause system instability, crashes, or potentially enable privilege escalation or other security breaches if exploited. However, no known exploits in the wild have been reported. The impact is limited to affected Linux kernel versions handling IPv6 AH6 packets with malformed routing headers.

Summary

CVE-2026-80844 addresses a vulnerability in the Linux kernel's xfrm subsystem, specifically in the AH6 (Authentication Header for IPv6) processing. The function ipv6_rearrange_rthdr() incorrectly assumes that the segments_left value in the routing header does not exceed the number of addresses described by hdrlen. For raw IPv6 HDRINCL packets, this assumption can be violated, allowing segments_left to be arbitrarily large (e.g., 255). This causes the function to move an address pointer backwards by thousands of bytes and perform a memmove() with an out-of-bounds length, resulting in memory corruption. The fix involves validating the segments_left invariant locally and propagating malformed-header errors to existing AH6 error paths.

References

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Exploitation evidence

What to do

Affected software

Description

Reports on CVE-2026-80844

AI analysisMachine-generated, updated 6 Nov 2026, 17:33 UTC

Public exploits and detectionGitHub proofs of concept

Technical details

References

Community reviews

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