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.

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Linux Linux unaffected
Version Status Constraints
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected
< 589a530ae44d0c80f523fcfd1a15af8087f27d35
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 affected
< f613e8b4afea0cd17c7168e8b00e25bc8d33175d
Linux Linux affected
Version Status Constraints
2.6.12 affected
—
0 unaffected
< 2.6.12
6.18.10 unaffected
≤ 6.18.*
6.19 unaffected
≤ *

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References
Link Providers
https://git.kernel.org/stable/c/589a530ae44d0c80f523fcfd1a15af8087f27d35 cve-icon cve-icon
https://git.kernel.org/stable/c/f613e8b4afea0cd17c7168e8b00e25bc8d33175d cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2026031817-CVE-2026-23255-fc51@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-23255 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-23255 cve-icon
History

Thu, 19 Mar 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Wed, 18 Mar 2026 18:00:00 +0000

Type Values Removed Values Added
Description 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.
Title net: add proper RCU protection to /proc/net/ptype
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-03-18T17:41:01.445Z

Reserved: 2026-01-13T15:37:45.990Z

Link: CVE-2026-23255

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-18T18:16:23.687

Modified: 2026-03-18T18:16:23.687

Link: CVE-2026-23255

cve-icon Redhat

Severity : Important

Publid Date: 2026-03-18T00:00:00Z

Links: CVE-2026-23255 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses

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