l2tp: fix tunnel and session refcount leak on seq_file release

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74735
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-26 15:16:52 UTC
Updated2026-09-21 14:17:20 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: l2tp: fix tunnel and session refcount leak on seq_file release In pppol2tp_proc_open() and l2tp_dfs_seq_open(), iteration state (pd->tunnel and pd->session) is kept in seq_file private data to allow iteration across multiple read() system calls. However, if userspace closes /proc/net/pppol2tp or /sys/kernel/debug/l2tp/tunnels before reading to end-of-file (EOF), any tunnel or session reference stored in pd->tunnel / pd->session is left un-dropped when seq_file private data is freed. Fix this by dropping any remaining pd->tunnel and pd->session references in pppol2tp_proc_release() and l2tp_dfs_seq_release() when closing the file.

Risk And Classification

EPSS: 0.001750000 probability, percentile 0.073000000 (date 2026-09-22)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 bdf83613781956cc39798ed08321f74ab0467f4d git Not specified
CNA Linux Linux affected 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 8c4fde01bcf91f22b9c7ded8c3e14addd7ddd500 git Not specified
CNA Linux Linux affected 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 ebe2774e956482dd3c70b8991f6f7654356339e6 git Not specified
CNA Linux Linux affected 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 9006c116dd111d457bf5d074990210f70a4ad2c8 git Not specified
CNA Linux Linux affected f6104e9ae04462523c372928b1173766a771ef95 git Not specified
CNA Linux Linux affected 7f8e401f9e612df2a95c1ef76217c00181389bb5 git Not specified
CNA Linux Linux affected c712ed63e9b33d9a282fbd92ce25c64918c3129f git Not specified
CNA Linux Linux affected 9a8863e8a8def9d88583cd9c60db38a008e6b8cf git Not specified
CNA Linux Linux affected 3.16.60 3.17 semver Not specified
CNA Linux Linux affected 4.16.6 4.17 semver Not specified
CNA Linux Linux affected 4.17 Not specified
CNA Linux Linux unaffected 4.17 semver Not specified
CNA Linux Linux unaffected 6.12.111 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.53 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.10 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/9006c116dd111d457bf5d074990210f70a4ad2c8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ebe2774e956482dd3c70b8991f6f7654356339e6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bdf83613781956cc39798ed08321f74ab0467f4d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8c4fde01bcf91f22b9c7ded8c3e14addd7ddd500 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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