netfilter: ctnetlink: fix refcount leak on table dump

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-38721
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-09-04 16:15:41 UTC
Updated2026-07-14 13:17:42 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix refcount leak on table dump There is a reference count leak in ctnetlink_dump_table(): if (res < 0) { nf_conntrack_get(&ct->ct_general); // HERE cb->args[1] = (unsigned long)ct; ... While its very unlikely, its possible that ct == last. If this happens, then the refcount of ct was already incremented. This 2nd increment is never undone. This prevents the conntrack object from being released, which in turn keeps prevents cnet->count from dropping back to 0. This will then block the netns dismantle (or conntrack rmmod) as nf_conntrack_cleanup_net_list() will wait forever. This can be reproduced by running conntrack_resize.sh selftest in a loop. It takes ~20 minutes for me on a preemptible kernel on average before I see a runaway kworker spinning in nf_conntrack_cleanup_net_list. One fix would to change this to: if (res < 0) { if (ct != last) nf_conntrack_get(&ct->ct_general); But this reference counting isn't needed in the first place. We can just store a cookie value instead. A followup patch will do the same for ctnetlink_exp_dump_table, it looks to me as if this has the same problem and like ctnetlink_dump_table, we only need a 'skip hint', not the actual object so we can apply the same cookie strategy there as well.

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: NVD-CWE-Other

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 586892e341fbf698e7cbaca293e1353957db725a git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 962518c6ca9f9a13df099cafa429f72f68ad61f0 git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 19b909a4b1452fb97e477d2f08b97f8d04095619 git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 41462f4cfc583513833f87f9ee55d12da651a7e3 git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 30cf811058552b8cd0e98dff677ef3f89d6d34ce git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 a2cb4df7872de069f809de2f076ec8e54d649fe3 git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 e14f72aa66c029db106921d621edcedef68e065b git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b git Not specified
CNA Linux Linux affected d205dc40798d97d63ad348bfaf7394f445d152d4 de788b2e6227462b6dcd0e07474e72c089008f74 git Not specified
CNA Linux Linux affected 2.6.18 Not specified
CNA Linux Linux unaffected 2.6.18 semver Not specified
CNA Linux Linux unaffected 5.4.297 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.241 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.190 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.149 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.103 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.43 6.12.* semver Not specified
CNA Linux Linux unaffected 6.15.11 6.15.* semver Not specified
CNA Linux Linux unaffected 6.16.2 6.16.* semver Not specified
CNA Linux Linux unaffected 6.17 * original_commit_for_fix Not specified
ADP Siemens SIMATIC CN 4100 affected V5.0 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/19b909a4b1452fb97e477d2f08b97f8d04095619 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/962518c6ca9f9a13df099cafa429f72f68ad61f0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/10/msg00008.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/a2cb4df7872de069f809de2f076ec8e54d649fe3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-082556.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/30cf811058552b8cd0e98dff677ef3f89d6d34ce 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/e14f72aa66c029db106921d621edcedef68e065b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
cert-portal.siemens.com/productcert/html/ssa-032379.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/586892e341fbf698e7cbaca293e1353957db725a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/de788b2e6227462b6dcd0e07474e72c089008f74 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/41462f4cfc583513833f87f9ee55d12da651a7e3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/10/msg00007.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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