CVE-2026-31420

Medium

In the Linux kernel, the following vulnerability has been resolved: bridge: mrp: reject zero test interval to avoid OOM panic br_mrp_start_test() and br_mrp_start_in_test() accept the user-supplied interval value from netlink without validation. When interval is 0, usecs_to_jiffies(0) yields 0, causing the delayed work (br_mrp_test_work_expired / br_mrp_in_test_work_expired) to reschedule itself with zero delay. This creates a tight loop on system_percpu_wq that allocates and transmits MRP test frames at maximum rate, exhausting all system memory and causing a kernel panic via OOM deadlock. The same zero-interval issue applies to br_mrp_start_in_test_parse() for interconnect test frames. Use NLA_POLICY_MIN(NLA_U32, 1) in the nla_policy tables for both IFLA_BRIDGE_MRP_START_TEST_INTERVAL and IFLA_BRIDGE_MRP_START_IN_TEST_INTERVAL, so zero is rejected at the netlink attribute parsing layer before the value ever reaches the workqueue scheduling code. This is consistent with how other bridge subsystems (br_fdb, br_mst) enforce range constraints on netlink attributes.

Package Linux Kernel
Published 2026-04-13
Last modified 2026-06-01
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness type

CWE-667

CVE-2026-31420 is a Improper Locking vulnerability

What is Improper Locking?

The product does not properly acquire or release a lock, which can lead to unexpected behaviour. Learn more on MITRE CWE

Affected versions

Linux kernel versions 5.8 and later are affected. Fixed in 6.12.92, 6.18.34, 6.19.12, 7.0 and their respective stable series.

Affected from
≥ 5.8
Fixed in
✓ 6.12.92 6.12.x ✓ 6.18.34 6.18.x ✓ 6.19.12 6.19.x ✓ 7.0

References

The following references provide additional information about CVE-2026-31420 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

4 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-31420?

    CVE-2026-31420 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as an Improper Locking flaw (CWE-667) . It affects Linux kernel versions from 5.8 onward and has been patched in 6.12.92, 6.18.34, 6.19.12 and others. CVE-2026-31420 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-31420?

    CVE-2026-31420 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2026-31420?

    Yes — CVE-2026-31420 has been patched. Fixed versions include 6.12.92, 6.18.34, 6.19.12 and others. If you are running Linux kernel 5.8 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-31420 actively exploited?

    No — CVE-2026-31420 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Improper Locking (CWE-667)?

    The product does not properly acquire or release a lock, which can lead to unexpected behaviour. View CWE-667 on MITRE CWE →

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