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  4. CVE 2026 23255 net add proper rcu protection to procnetptype
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Back to active CVEs
Medium ยท CVSS 5.5CVE-2026-23255

net: add proper RCU protection to /proc/net/ptypeCVE-2026-23255

Answer in brief

CVE-2026-23255 records a Medium severity (CVSS 5.5) vulnerability in net: add proper RCU protection to /proc/net/ptype. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Mar 18, 2026Updated Oct 15, 2026Source checked Oct 23, 2026First seen by HOL Sep 8, 2026Material review Oct 15, 2026
Upstream Advisory

Key facts

Risk
Medium ยท CVSS 5.5
Exploitation
Not marked as known exploited
Affected software
23 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic), Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.

Affected products and reported versions
ProductAffected versionsFixed versions
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc1:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc2:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc3:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc4:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc5:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc6:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc7:*:*:*:*:*:*Not reportedNot reported
cpe:2.3:o:linux:linux_kernel:6.19:rc8:*:*:*:*:*:*Not reportedNot reported
Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Linux/Linuxgeneric>=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e974a10a52618f7f57a4bce173a0ed96acd4e5dc || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <002a73470b56848e4c81efeaaedd471e92d66d8d || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dcefd3f0b9ed8288654c75254bdcee8e1085e861 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <589a530ae44d0c80f523fcfd1a15af8087f27d35 || >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f613e8b4afea0cd17c7168e8b00e25bc8d33175de974a10a52618f7f57a4bce173a0ed96acd4e5dc, 002a73470b56848e4c81efeaaedd471e92d66d8d, dcefd3f0b9ed8288654c75254bdcee8e1085e861, 589a530ae44d0c80f523fcfd1a15af8087f27d35, f613e8b4afea0cd17c7168e8b00e25bc8d33175d
Linux/Linuxgeneric2.6.12Not reported
Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.7 <**
Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPgeneric>=V3.1.7 <**
Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystemgeneric>=0 <**
Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.6 <**
Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFPgeneric>=V3.1.7 <**

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux, Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP.
  2. 2Review the reported fix. Update Linux/Linux to e974a10a52618f7f57a4bce173a0ed96acd4e5dc; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP to *; Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to *; Siemens/SIPLUS S7-1500 CPU 1518-4 PN/DP MFP to * if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Mar 18, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Oct 15, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Sep 8, 2026

Sources and claim methodology

  • Source referencecert-portal.siemens.com
  • Source referencecert-portal.siemens.com
  • Source referencecert-portal.siemens.com
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
NVD-CWE-noinfo
Source
CVE List V5
Source checked
Oct 23, 2026
References
8 linked sources
Open source record