net: mctp: hold a reference to the route device in mctp_route_lookup() (CVE-2026-80995) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-80995

net: mctp: hold a reference to the route device in mctp_route_lookup()

Answer in brief

CVE-2026-80995 records a Unknown severity vulnerability in net: mctp: hold a reference to the route device in mctp_route_lookup(). 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 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 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	>=22cb45afd221b9e4f2a1dcc74a8ff645b7293aa1 <cc561f8af25586300c2f9d285babb163b866b293 \|\| >=22cb45afd221b9e4f2a1dcc74a8ff645b7293aa1 <408da1df18116c971c3392e21e50586688cd3fbf	cc561f8af25586300c2f9d285babb163b866b293, 408da1df18116c971c3392e21e50586688cd3fbf
Linux/Linuxgeneric	7.1	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to cc561f8af25586300c2f9d285babb163b866b293 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: net: mctp: hold a reference to the route device in mctp_route_lookup() mctp_route_lookup() uses rt->dev without holding a reference on it. mctp_route_lookup_single() returns the route under RCU only, so the route's device can be torn down concurrently: mctp_dev_put() drops the last reference and synchronously kfree()s mdev->addrs. mctp_dev_saddr() then reads rt->dev->addrs[0], giving a use-after-free reachable by an unprivileged local AF_MCTP user on the receive/forwarding path (no CAP_NET_RAW required): BUG: KASAN: slab-use-after-free in mctp_route_lookup Read of size 1 at addr ... by task mctp_uaf/... mctp_route_lookup mctp_pkttype_receive Freed by task ...: kfree mctp_dev_put mctp_dev_notify In the same window mctp_dst_from_route() -> mctp_dev_hold() also increments a refcount that has already reached zero ("refcount_t: addition on 0 ... mctp_dev_hold"). This reintroduces the use-after-free class of CVE-2023-3439: the source address lookup was moved ahead of the point where the destination takes its device reference. Take a reference with refcount_inc_not_zero() before touching rt->dev, skip a device that is already dead, and drop the reference once the destination has taken its own.

Quoted source text, attributed separately from HOL analysis.