Vulnerability in Linux kernel (CVE-2026-68420)
Summary
Vulnerability in Linux kernel (CVE-2026-68420). Confidential information can be exposed externally.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
xfrm: reject optional IPTFS templates in outbound policies
syzbot reported a stack-out-of-bounds read in xfrm_state_find()
which flows from xfrm_tmpl_resolve_one().
Commit 3d776e31c841 ("xfrm: Reject optional tunnel/BEET mode
templates in outbound policies") disallowed optional tunnel and
BEET in outbound policies to prevent this. Later when IPTFS
added, it was not covered by that fix and can still trigger
the out-of-bounds read;
Extend the check to disallow optional IPTFS in outbound policies
as well. IPTFS should be identical to tunnel mode.
IN and FWD policies are not affected: xfrm_tmpl_resolve_one()
is only reachable via the outbound path.
Reproducer, before:
ip link add dummy0 type dummy
ip link set dummy0 up
ip addr add 10.1.1.1/24 dev dummy0
ip xfrm policy add src 10.1.1.1/32 dst 10.1.1.2/32 dir out tmpl
src fc00::dead:1 dst fc00::dead:2 proto esp reqid 1 mode iptfs
level use tmpl src fc00::dead:1 dst fc00::dead:2 proto esp reqid
2 mode transport
ping -W 1 -c 1 10.1.1.2
PING 10.1.1.2 (10.1.1.2) 56(84) bytes of data.
[ 64.168420] ==================================================================
[ 64.169977] BUG: KASAN: stack-out-of-bounds in __xfrm6_addr_hash+0x11e/0x170
[ 64.169977] Read of size 4 at addr ffff88800e1ffd20 by task ping/2844
[ 64.169977] CPU: 2 UID: 0 PID: 2844 Comm: ping Not tainted 7.1.0-rc7-00180-geb23b588430a #98 PREEMPT(full)
[ 64.169977] Hardware name: QEM…
Source: GitHub Security Advisories (Global) 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-2026-68420 has been found in Linux kernel.
Confidential information can be exposed externally. CVSS score: 7.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-68420" on the vendor's site.
CVE-2026-68420 (Linux kernel) — CVSS v3 7.1
Attack vector: local / 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 (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: High (CVSS 7.1/10). Confidential information can be exposed externally.
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-2026-68420 linux-lts Fixed in: 6.18.43-r0
- Debian DEBIAN-CVE-2026-68420 linux Fixed in: 7.1.6-1
- Ubuntu UBUNTU-CVE-2026-68420 linux-hwe-edge
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 github.com