---
id: CVE-2026-43139
title: 'xfrm6: fix uninitialized saddr in xfrm6_get_saddr()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  xfrm6: fix uninitialized saddr in xfrm6_get_saddr()

  xfrm6_get_saddr() does not check the return value of
  ipv6_dev_get_saddr(). When ipv6_dev_get_saddr() fails to find …
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    4f28141786e1fe884ce42a5197ba9beed540f0ea
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    6535867673bf301d52aa00593a4d1d18cc3922fa
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    eb2ee15290af14c60b45cf2b73f5687d1d077d9b
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    719918fc88df6da023dfff370cd965151a5afd7f
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    dc0abce055134cb83b0d981d31ceb20dda419787
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    c7221e7bd8fc2ef38a0b27be580d9d202281306b
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    3dcd1664ac15eee6a690daec7c4ffc59190406f7
  - >-
    Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 <
    1799d8abeabc68ec05679292aaf6cba93b343c05
  - Linux 2.6.19
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-16T15:15:07.789549Z'
published: '2026-05-06'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:20:34.389Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43139'
references:
  - url: 'https://git.kernel.org/stable/c/4f28141786e1fe884ce42a5197ba9beed540f0ea'
  - url: 'https://git.kernel.org/stable/c/6535867673bf301d52aa00593a4d1d18cc3922fa'
  - url: 'https://git.kernel.org/stable/c/eb2ee15290af14c60b45cf2b73f5687d1d077d9b'
  - url: 'https://git.kernel.org/stable/c/719918fc88df6da023dfff370cd965151a5afd7f'
  - url: 'https://git.kernel.org/stable/c/dc0abce055134cb83b0d981d31ceb20dda419787'
  - url: 'https://git.kernel.org/stable/c/c7221e7bd8fc2ef38a0b27be580d9d202281306b'
  - url: 'https://git.kernel.org/stable/c/3dcd1664ac15eee6a690daec7c4ffc59190406f7'
  - url: 'https://git.kernel.org/stable/c/1799d8abeabc68ec05679292aaf6cba93b343c05'
tags:
  - cve.org
epss: 0.00375
epssPercentile: 0.29876
ingestedAt: '2026-10-16T17:24:46.684Z'
---

## Overview

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

xfrm6: fix uninitialized saddr in xfrm6_get_saddr()

xfrm6_get_saddr() does not check the return value of
ipv6_dev_get_saddr(). When ipv6_dev_get_saddr() fails to find a suitable
source address (returns -EADDRNOTAVAIL), saddr->in6 is left
uninitialized, but xfrm6_get_saddr() still returns 0 (success).

This causes the caller xfrm_tmpl_resolve_one() to use the uninitialized
address in xfrm_state_find(), triggering KMSAN warning:

=====================================================
BUG: KMSAN: uninit-value in xfrm_state_find+0x2424/0xa940
 xfrm_state_find+0x2424/0xa940
 xfrm_resolve_and_create_bundle+0x906/0x5a20
 xfrm_lookup_with_ifid+0xcc0/0x3770
 xfrm_lookup_route+0x63/0x2b0
 ip_route_output_flow+0x1ce/0x270
 udp_sendmsg+0x2ce1/0x3400
 inet_sendmsg+0x1ef/0x2a0
 __sock_sendmsg+0x278/0x3d0
 __sys_sendto+0x593/0x720
 __x64_sys_sendto+0x130/0x200
 x64_sys_call+0x332b/0x3e70
 do_syscall_64+0xd3/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Local variable tmp.i.i created at:
 xfrm_resolve_and_create_bundle+0x3e3/0x5a20
 xfrm_lookup_with_ifid+0xcc0/0x3770
=====================================================

Fix by checking the return value of ipv6_dev_get_saddr() and propagating
the error.

## Affected

- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < 4f28141786e1fe884ce42a5197ba9beed540f0ea`
- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < 6535867673bf301d52aa00593a4d1d18cc3922fa`
- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < eb2ee15290af14c60b45cf2b73f5687d1d077d9b`
- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < 719918fc88df6da023dfff370cd965151a5afd7f`
- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < dc0abce055134cb83b0d981d31ceb20dda419787`
- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < c7221e7bd8fc2ef38a0b27be580d9d202281306b`
- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < 3dcd1664ac15eee6a690daec7c4ffc59190406f7`
- `Linux >= a1e59abf824969554b90facd44a4ab16e265afa4 < 1799d8abeabc68ec05679292aaf6cba93b343c05`
- `Linux 2.6.19`

## Remediation

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