mptcp: syncookies: remember the request backup flag (CVE-2026-97568) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-97568

mptcp: syncookies: remember the request backup flag

Answer in brief

CVE-2026-97568 records a Unknown severity vulnerability in mptcp: syncookies: remember the request backup flag. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 25, 2026Updated Sep 25, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 25, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <61178d0b85b4b1b53e78b06e89d018d22d102f88 \|\| >=efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <00b2bd518911e0daab00f4749cce68c191ccebb4 \|\| >=efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <06d649f9cd03a9f8e768a658b20acf8d2c8022e0 \|\| >=efd340bf3d7779a3a8ec954d8ec0fb8a10f24982 <b76c0e28b392620dfbaf92cdeedbf115820b44cb \|\| 1008f2bcbc8e461c1df3aebba30ac4f616ebe570 \|\| 6f01f41b6a492ddf2da7609967cfaf57e7ca48a7 \|\| 09176f80995105c62939728fbad5c437d61e7ff4 \|\| 8ed3e34c766e8264d5d2e0436f86c51604d6a8a7 \|\| 73e2baa301ee3f62ff971e68877adeb37f98cc67 \|\| >=5.10.224 <5.11 \|\| >=5.15.165 <5.16 \|\| >=6.1.104 <6.2 \|\| >=6.6.45 <6.7 \|\| >=6.10.4 <6.11	61178d0b85b4b1b53e78b06e89d018d22d102f88, 00b2bd518911e0daab00f4749cce68c191ccebb4, 06d649f9cd03a9f8e768a658b20acf8d2c8022e0, b76c0e28b392620dfbaf92cdeedbf115820b44cb, 5.11, 5.16, 6.2, 6.7, 6.11
Linux/Linuxgeneric	6.11	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 61178d0b85b4b1b53e78b06e89d018d22d102f88 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: mptcp: syncookies: remember the request backup flag Instead of using an uninitialised bit when copying the info in subflow_ulp_clone(). To fix this, no need to extend the join_entry structure: backup is coming from struct mptcp_subflow_request_sock, only one bit. Do the same here by using one bit for both.

Quoted source text, attributed separately from HOL analysis.