CVE-2026-23255

Medium

In the Linux kernel, the following vulnerability has been resolved: net: add proper RCU protection to /proc/net/ptype Yin Fengwei reported an RCU stall in ptype_seq_show() and provided a patch. Real issue is that ptype_seq_next() and ptype_seq_show() violate RCU rules. ptype_seq_show() runs under rcu_read_lock(), and reads pt->dev to get device name without any barrier. At the same time, concurrent writers can remove a packet_type structure (which is correctly freed after an RCU grace period) and clear pt->dev without an RCU grace period. Define ptype_iter_state to carry a dev pointer along seq_net_private: struct ptype_iter_state { struct seq_net_private p; struct net_device *dev; // added in this patch }; We need to record the device pointer in ptype_get_idx() and ptype_seq_next() so that ptype_seq_show() is safe against concurrent pt->dev changes. We also need to add full RCU protection in ptype_seq_next(). (Missing READ_ONCE() when reading list.next values) Many thanks to Dong Chenchen for providing a repro.

Package Linux Kernel
Published 2026-03-18
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

Affected versions

Linux kernel versions 2.6.12 and later are affected. Fixed in 6.1.175, 6.6.136, 6.12.80, 6.18.10, 6.19 and their respective stable series.

Affected from
≥ 2.6.12
Fixed in
✓ 6.1.175 6.1.x ✓ 6.6.136 6.6.x ✓ 6.12.80 6.12.x ✓ 6.18.10 6.18.x ✓ 6.19

References

The following references provide additional information about CVE-2026-23255 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

5 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-23255?

    CVE-2026-23255 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 2.6.12 onward and has been patched in 6.1.175, 6.6.136, 6.12.80 and others. CVE-2026-23255 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-23255?

    CVE-2026-23255 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-2026-23255?

    Yes — CVE-2026-23255 has been patched. Fixed versions include 6.1.175, 6.6.136, 6.12.80 and others. If you are running Linux kernel 2.6.12 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-23255 actively exploited?

    No — CVE-2026-23255 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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