Vulnerability in Linux Kernel (CVE-2026-64422)
Summary
Vulnerability in Linux Kernel (CVE-2026-64422). Confidential information can be exposed externally. Exploitable via net.ipv4.tcp_reordering.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes
Reject invalid net.ipv4.tcp_reordering values before they reach TCP
socket state. The sysctl is stored as an int but copied into the
u32 tp->reordering field for new sockets, so negative writes wrap
to large values.
With tcp_mtu_probing=2, the wrapped value can overflow the
tcp_mtu_probe() size calculation and drive the MTU probing path into
an out-of-bounds read. Route tcp_reordering writes through
proc_dointvec_minmax() and require it to be at least 1. Also require
tcp_max_reordering to be at least 1 so the configured maximum cannot
become negative either.
When registering the table for a non-init network namespace, relocate
extra2 pointers that refer into init_net.ipv4 so the
tcp_reordering upper bound follows that namespace's
tcp_max_reordering.
Harden tcp_mtu_probe() itself by computing size_needed as u64.
This keeps the send queue and window checks from being bypassed through
signed integer overflow.
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-2026-64422 has been found in Linux Kernel.
Attackers can target a specific entry point like net.ipv4.tcp_reordering over the network to misuse the product.
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-2026-64422" on the vendor's site.
CVE-2026-64422 (Linux Kernel) — CWE-190 / CVSS v3 7.1
Attack vector: local / no user interaction
Attack surface: net.ipv4.tcp_reordering / int / u32 / tcp_reordering
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-190) exists in Linux Kernel. Attackers reach the vulnerable code path via net.ipv4.tcp_reordering.
Check the vendor advisory for the affected versions of Linux Kernel. Attack surface: net.ipv4.tcp_reordering / int / u32 / tcp_reordering.
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。
References
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- patch git.kernel.org
- web nvd.nist.gov
- web github.com
- web cert-portal.siemens.com
- web cert-portal.siemens.com