l2tp: fix tunnel and session refcount leak on seq_file release (CVE-2026-74735) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-74735

l2tp: fix tunnel and session refcount leak on seq_file release

Answer in brief

CVE-2026-74735 records a Unknown severity vulnerability in l2tp: fix tunnel and session refcount leak on seq_file release. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

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

Published Aug 26, 2026Updated Aug 26, 2026Source checked Aug 26, 2026First seen by HOL Aug 26, 2026Material review Aug 26, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. 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). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 <ebe2774e956482dd3c70b8991f6f7654356339e6 \|\| >=0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 <9006c116dd111d457bf5d074990210f70a4ad2c8 \|\| f6104e9ae04462523c372928b1173766a771ef95 \|\| 7f8e401f9e612df2a95c1ef76217c00181389bb5 \|\| c712ed63e9b33d9a282fbd92ce25c64918c3129f \|\| 9a8863e8a8def9d88583cd9c60db38a008e6b8cf \|\| >=3.16.60 <3.17 \|\| >=4.16.6 <4.17	ebe2774e956482dd3c70b8991f6f7654356339e6, 9006c116dd111d457bf5d074990210f70a4ad2c8, 3.17, 4.17
Linux/Linuxgeneric	4.17	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to ebe2774e956482dd3c70b8991f6f7654356339e6 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 26, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 26, 2026

Sources and claim methodology

Upstream source description

In 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.

Quoted source text, attributed separately from HOL analysis.