CVE-2026-43139

High

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.

Package Linux Kernel
Published 2026-05-06
Last modified 2026-05-13
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

8.6

out of 10
High
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
High
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Weakness type

CWE-908

CVE-2026-43139 is classified as CWE-908

See CWE-908 on MITRE CWE for full details on this weakness type.

Affected versions

Linux kernel versions 2.6.19 and later are affected. Fixed in 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16, 6.19.6, 7.0 and their respective stable series.

Affected from
≥ 2.6.19
Fixed in
✓ 5.10.252 5.10.x ✓ 5.15.202 5.15.x ✓ 6.1.165 6.1.x ✓ 6.6.128 6.6.x ✓ 6.12.75 6.12.x ✓ 6.18.16 6.18.x ✓ 6.19.6 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-43139 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

8 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-43139?

    CVE-2026-43139 is a High severity Linux kernel vulnerability with a CVSS score of 8.6 out of 10 . It affects Linux kernel versions from 2.6.19 onward and has been patched in 5.10.252, 5.15.202, 6.1.165 and others. CVE-2026-43139 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-43139?

    CVE-2026-43139 has a CVSS score of 8.6 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H .

  • Is there a patch available for CVE-2026-43139?

    Yes — CVE-2026-43139 has been patched. Fixed versions include 5.10.252, 5.15.202, 6.1.165 and others. If you are running Linux kernel 2.6.19 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-43139 actively exploited?

    No — CVE-2026-43139 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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