Vulnerability in Linux kernel (CVE-2026-43139)
Summary
Vulnerability in Linux kernel (CVE-2026-43139). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-43139 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 8.6/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-43139" on the vendor's site.
CVE-2026-43139 (Linux kernel) — CWE-908 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-908) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 8.6/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-43139 linux-lts Fixed in: 6.1.167-r0
- Debian DEBIAN-CVE-2026-43139 linux Fixed in: 5.10.257-1
- Ubuntu UBUNTU-CVE-2026-43139 linux
References
- advisory nvd.nist.gov
- advisory github.com
- package git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web github.com