---
id: CVE-2026-89783
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full

  The depth check in xfrm6_input_addr() is off by one:

    if (1 + sp->len == XFRM_MAX_DEPTH)
    …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full

  The depth check in xfrm6_input_addr() is off by one:

    if (1 + sp->len == XFRM_MAX_DEPTH)
    …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    91fc387f63c00ddfb5221127a17bac97549a8343
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    68e8737fe8e72f085c608cff322b3d2de8340af1
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    8fe2c53fb81f5ad5be43af2ad09583f7c78b4b77
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    bdcda866c89f9a8b1acdabf02d26cde9fbe501d8
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    48996649222e95008cdb98cd58579e3fc8e5ee06
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    0f679e0523ddfff3fb554336ceb874b0e51e9cd3
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    5f35a29a5eed3d80befd32050843ac88dea3d61a
  - >-
    Linux >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5 <
    5d9e3bf34fec9a5d237e4b7cef4a707bc2e091bc
  - Linux 2.6.25
published: '2026-09-16'
updated: '2026-09-16'
sourceUpdated: '2026-09-16T15:18:08.720'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-89783'
references:
  - url: 'https://git.kernel.org/stable/c/0f679e0523ddfff3fb554336ceb874b0e51e9cd3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/48996649222e95008cdb98cd58579e3fc8e5ee06'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5d9e3bf34fec9a5d237e4b7cef4a707bc2e091bc'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/5f35a29a5eed3d80befd32050843ac88dea3d61a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/68e8737fe8e72f085c608cff322b3d2de8340af1'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/8fe2c53fb81f5ad5be43af2ad09583f7c78b4b77'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/91fc387f63c00ddfb5221127a17bac97549a8343'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/bdcda866c89f9a8b1acdabf02d26cde9fbe501d8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-16T08:52:29.592Z'
epss: 0.00704
epssPercentile: 0.51904
---

## Overview

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

xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full

The depth check in xfrm6_input_addr() is off by one:

  if (1 + sp->len == XFRM_MAX_DEPTH)
          goto drop;
  ...
  sp->xvec[sp->len++] = x;

xfrm_input() can leave sp->len == XFRM_MAX_DEPTH, and the transport-mode
receive path re-enters IPv6 input via xfrm_trans_reinject() with that
secpath preserved. If the inner packet carries a destination-options HAO
option or a type-2 routing header, xfrm6_input_addr() is called with
sp->len == XFRM_MAX_DEPTH; the check (1 + 6 == 6) is false, so
sp->xvec[sp->len++] writes one slot past the 6-element xvec[]. The write
stays within the sec_path allocation (invisible to KASAN); UBSAN_BOUNDS
flags it and panics under panic_on_warn.

Use "sp->len >= XFRM_MAX_DEPTH", matching xfrm_input(). This also
restores one chain level the old check rejected at sp->len == 5.

  UBSAN: array-index-out-of-bounds in net/ipv6/xfrm6_input.c:309:10
  index 6 is out of range for type 'xfrm_state *[6]'

## Remediation

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