mptcp: pm: kernel: drop pending ADD_ADDR when removing ID0 (CVE-2026-97566) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-97566

mptcp: pm: kernel: drop pending ADD_ADDR when removing ID0

Answer in brief

CVE-2026-97566 records a Unknown severity vulnerability in mptcp: pm: kernel: drop pending ADD_ADDR when removing ID0. 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	>=740d798e8767d8a449902b1a1bbc70facfce19b5 <d4a67a880654e1bfe318a31bea0bdbb026a09ade \|\| >=740d798e8767d8a449902b1a1bbc70facfce19b5 <545616b4e7325be3c61fc082538cb06d14f7b1db \|\| >=740d798e8767d8a449902b1a1bbc70facfce19b5 <2ac7d6e620764f1fc79eb4edd3610a7a661981ca	d4a67a880654e1bfe318a31bea0bdbb026a09ade, 545616b4e7325be3c61fc082538cb06d14f7b1db, 2ac7d6e620764f1fc79eb4edd3610a7a661981ca
Linux/Linuxgeneric	5.13	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to d4a67a880654e1bfe318a31bea0bdbb026a09ade 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: pm: kernel: drop pending ADD_ADDR when removing ID0 The in-kernel MPTCP path manager can leave a stale ADD_ADDR announcement entry alive when removing the id 0 endpoint. This happens because the id 0 removal path does not tear down pending announcements, unlike the non-zero id path. When the PM later reselects id 0 after adding another signal endpoint, it finds the stale anno_list entry and hits WARN_ON_ONCE(mptcp_pm_is_kernel()) in mptcp_pm_announced_alloc(). Root cause: asymmetry between removal paths. - Non-zero id path: mptcp_nl_remove_subflow_and_signal_addr() calls mptcp_pm_remove_announced() to clean up. - Id 0 path: mptcp_nl_remove_id_zero_address() skips cleanup entirely. Fix by making the id 0 path symmetric: call mptcp_pm_announced_remove() and decrement add_addr_signaled before queuing the RM_ADDR. Subtle detail: signal endpoints are stored in anno_list with port 0, but msk_local carries the connection's local port. In other words, entries linked to ID0 paths should have port == 0. A follow-up patch will ensure that. mptcp_pm_announced_remove() uses use_port=true for comparison. So clear the port before the lookup.

Quoted source text, attributed separately from HOL analysis.