---
id: CVE-2026-80844
title: 'xfrm: ah6: validate routing header segments_left'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  xfrm: ah6: validate routing header segments_left

  AH6 rearranges routing-header addresses before computing or verifying the
  ICV. ipv6_rearrange_rthdr() assumes that seg…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    2dc650956e4e163b879b3fb1027f9557abc5c985
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    48b0e36cf54358276ee7aa897034c973097d2bc9
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1b7e066eabcc7d6d8f476c34739b45932f2f4c31
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    f00df8500e5a36ba70d336fd34bd2152ea074e5f
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    1516e31ac458a738be485620579d8f7fb2700fcb
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    6733ae71268a27d598cfb3f3339a3c950b9b656d
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    0bf11081ad3753938a2b48723ce6298dbac743a1
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    46640c814f25f096b0b0045ca50e1b7030cd8a30
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    7bad4bda74dc4713f398d3b7624ff05478e3a568
  - Linux 2.6.12
exploitAvailable: true
published: '2026-09-04'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:44:37.342Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80844'
references:
  - url: 'https://git.kernel.org/stable/c/2dc650956e4e163b879b3fb1027f9557abc5c985'
  - url: 'https://git.kernel.org/stable/c/48b0e36cf54358276ee7aa897034c973097d2bc9'
  - url: 'https://git.kernel.org/stable/c/1b7e066eabcc7d6d8f476c34739b45932f2f4c31'
  - url: 'https://git.kernel.org/stable/c/f00df8500e5a36ba70d336fd34bd2152ea074e5f'
  - url: 'https://git.kernel.org/stable/c/1516e31ac458a738be485620579d8f7fb2700fcb'
  - url: 'https://git.kernel.org/stable/c/6733ae71268a27d598cfb3f3339a3c950b9b656d'
  - url: 'https://git.kernel.org/stable/c/0bf11081ad3753938a2b48723ce6298dbac743a1'
  - url: 'https://git.kernel.org/stable/c/46640c814f25f096b0b0045ca50e1b7030cd8a30'
  - url: 'https://git.kernel.org/stable/c/7bad4bda74dc4713f398d3b7624ff05478e3a568'
tags:
  - cve.org
  - exploit-available
epss: 0.00434
epssPercentile: 0.36202
exploits:
  github: 3
  githubRepos:
    - 'https://github.com/suominen/dirtyah6'
    - 'https://github.com/0xBlackash/CVE-2026-80844'
    - 'https://github.com/HORKimhab/CVE-2026-80844'
  checkedAt: '2026-10-19T09:16:36.569Z'
ingestedAt: '2026-10-19T09:16:01.497Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

xfrm: ah6: validate routing header segments_left

AH6 rearranges routing-header addresses before computing or verifying the
ICV. ipv6_rearrange_rthdr() assumes that segments_left is not larger than
the number of addresses described by the routing header's hdrlen field.

That assumption does not hold for raw IPv6 HDRINCL packets. A packet with
hdrlen equal to 2 describes one address, but can carry an arbitrary
segments_left value. With segments_left equal to 255, the function moves
its address pointer 4,064 bytes backwards and passes a 4,064-byte length to
memmove(), resulting in an out-of-bounds access.

Validate the invariant locally before modifying the routing header or
performing any address-pointer arithmetic, and propagate malformed-header
errors to the existing AH6 input and output error paths.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2dc650956e4e163b879b3fb1027f9557abc5c985`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 48b0e36cf54358276ee7aa897034c973097d2bc9`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1b7e066eabcc7d6d8f476c34739b45932f2f4c31`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f00df8500e5a36ba70d336fd34bd2152ea074e5f`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1516e31ac458a738be485620579d8f7fb2700fcb`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6733ae71268a27d598cfb3f3339a3c950b9b656d`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 0bf11081ad3753938a2b48723ce6298dbac743a1`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 46640c814f25f096b0b0045ca50e1b7030cd8a30`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7bad4bda74dc4713f398d3b7624ff05478e3a568`
- `Linux 2.6.12`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.