Vulnerability in Linux kernel (CVE-2026-45905)
Summary
Vulnerability in Linux kernel (CVE-2026-45905). 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:
xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path
icmp_route_lookup() performs multiple route lookups to find a suitable
route for sending ICMP error messages, with special handling for XFRM
(IPsec) policies.
The lookup sequence is:
- First, lookup output route for ICMP reply (dst = original src)
- Pass through xfrm_lookup() for policy check
- If blocked (-EPERM) or dst is not local, enter "reverse path"
- In reverse path, call xfrm_decode_session_reverse() to get fl4_dec
which reverses the original packet's flow (saddr<->daddr swapped) - If fl4_dec.saddr is local (we are the original destination), use
__ip_route_output_key() for output route lookup - If fl4_dec.saddr is NOT local (we are a forwarding node), use
ip_route_input() to simulate the reverse packet's input path - Finally, pass rt2 through xfrm_lookup() with XFRM_LOOKUP_ICMP flag
The bug occurs in step 6: ip_route_input() is called with fl4_dec.daddr
(original packet's source) as destination. If this address becomes local
between the initial check and ip_route_input() call (e.g., due to
concurrent "ip addr add"), ip_route_input() returns a LOCAL route with
dst.output set to ip_rt_bug.
This route is then used for ICMP output, causing dst_output() to call
ip_rt_bug(), triggering a WARN_ON:
------------[ cut here ]------------
WARNING: net/ipv4/route.c:1275 at ip_rt_bug+0x21/0x30, CPU#1
Call Trace:
ip_push_pending…
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-2026-45905 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure. CVSS score: 4.7/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-45905" on the vendor's site.
CVE-2026-45905 (Linux kernel) — CWE-362 / CVSS v3 4.7
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 (CWE-362) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: Medium (CVSS 4.7/10). 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-2026-45905 linux-lts Fixed in: 6.1.167-r0
- Debian DEBIAN-CVE-2026-45905 linux
- Ubuntu UBUNTU-CVE-2026-45905 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 github.com