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Fencer Vulns
medium 5.5

CVE-2025-37816 json

mei: vsc: Fix fortify-panic caused by invalid counted_by() use

published 2025-05-08 18 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-13987

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

mei: vsc: Fix fortify-panic caused by invalid counted_by() use

gcc 15 honors the __counted_by(len) attribute on vsc_tp_packet.buf[] and the vsc-tp.c code is using this in a wrong way. len does not contain the available size in the buffer, it contains the actual packet length *without* the crc. So as soon as vsc_tp_xfer() tries to add the crc to buf[] the fortify-panic handler gets triggered:

[ 80.842193] memcpy: detected buffer overflow: 4 byte write of buffer size 0 [ 80.842243] WARNING: CPU: 4 PID: 272 at lib/string_helpers.c:1032 __fortify_report+0x45/0x50 ... [ 80.843175] __fortify_panic+0x9/0xb [ 80.843186] vsc_tp_xfer.cold+0x67/0x67 [mei_vsc_hw] [ 80.843210] ? seqcount_lockdep_reader_access.constprop.0+0x82/0x90 [ 80.843229] ? lockdep_hardirqs_on+0x7c/0x110 [ 80.843250] mei_vsc_hw_start+0x98/0x120 [mei_vsc] [ 80.843270] mei_reset+0x11d/0x420 [mei]

The easiest fix would be to just drop the counted-by but with the exception of the ack buffer in vsc_tp_xfer_helper() which only contains enough room for the packet-header, all other uses of vsc_tp_packet always use a buffer of VSC_TP_MAX_XFER_SIZE bytes for the packet.

Instead of just dropping the counted-by, split the vsc_tp_packet struct definition into a header and a full-packet definition and use a fixed size buf[] in the packet definition, this way fortify-source buffer overrun checking still works when enabled.

Patch / fix

  • Linux Linux 6.12.26, 6.14.5, 6.15
  • linux Debian 14, Debian 13 6.12.27-1

debian advisories DEBIAN-CVE-2025-37816

  • linux Ubuntu 24.04 LTS 6.8.0-100.100
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1046.49
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1047.50
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1043.48
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1044.44
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1046.52
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1030.33
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1047.51

ubuntu advisories UBUNTU-CVE-2025-37816

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.8.1
  • kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.8.1
  • kernel-source-rt Real Time Module 15 SP7 6.4.0-150700.7.8.1
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.6.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.6.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.6.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.6.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.6.1

suse advisories SUSE-SU-2025:02333-1SUSE-SU-2025:02307-1SUSE-SU-2025:02254-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-37816 updated cvss 5.5

kernel: mei: vsc: Fix fortify-panic caused by invalid counted_by() use

  • Red Hat Enterprise Linux 10 kernel
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.