CVE-2026-46086

Medium

In the Linux kernel, the following vulnerability has been resolved: net: bridge: use a stable FDB dst snapshot in RCU readers Local FDB entries can be rewritten in place by `fdb_delete_local()`, which updates `f->dst` to another port or to `NULL` while keeping the entry alive. Several bridge RCU readers inspect `f->dst`, including `br_fdb_fillbuf()` through the `brforward_read()` sysfs path. These readers currently load `f->dst` multiple times and can therefore observe inconsistent values across the check and later dereference. In `br_fdb_fillbuf()`, this means a concurrent local-FDB update can change `f->dst` after the NULL check and before the `port_no` dereference, leading to a NULL-ptr-deref. Fix this by taking a single `READ_ONCE()` snapshot of `f->dst` in each affected RCU reader and using that snapshot for the rest of the access sequence. Also publish the in-place `f->dst` updates in `fdb_delete_local()` with `WRITE_ONCE()` so the readers and writer use matching access patterns.

Package Linux Kernel
Published 2026-05-27
Last modified 2026-06-24
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-476

CVE-2026-46086 is a NULL Pointer Dereference vulnerability

What is NULL Pointer Dereference?

The product dereferences a pointer that it expects to be valid but is NULL, typically causing a crash. Learn more on MITRE CWE

Affected versions

Linux kernel versions 3.14 and later are affected. Fixed in 5.10.259, 5.15.210, 6.1.176, 6.6.140, 6.12.86, 6.18.27, 7.0.4, 7.1 and their respective stable series.

Affected from
≥ 3.14
Fixed in
✓ 5.10.259 5.10.x ✓ 5.15.210 5.15.x ✓ 6.1.176 6.1.x ✓ 6.6.140 6.6.x ✓ 6.12.86 6.12.x ✓ 6.18.27 6.18.x ✓ 7.0.4 7.0.x ✓ 7.1

References

8 total
Showing 5 of 8 references View all on NVD

Frequently asked questions

  • What is CVE-2026-46086?

    CVE-2026-46086 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 , classified as a NULL Pointer Dereference flaw (CWE-476) . It affects Linux kernel versions from 3.14 onward and has been patched in 5.10.259, 5.15.210, 6.1.176 and others. CVE-2026-46086 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-46086?

    CVE-2026-46086 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-2026-46086?

    Yes. CVE-2026-46086 has been patched. Fixed versions include 5.10.259, 5.15.210, 6.1.176 and others. If you are running Linux kernel 3.14 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-46086 actively exploited?

    No. CVE-2026-46086 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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