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CVE-2026-74735· NVD / CVE Program· CNA Linux

l2tp: fix tunnel and session refcount leak on seq_file release

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.

—No exploit Fix available
Published
Aug 26, 2026
Updated
Sep 21, 2026
EPSS
0.2% · 10th percentile
CWE
—
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Action score

0

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Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

Noroxi analysis

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Affected systems

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • f6104e9ae04462523c372928b1173766a771ef95, 7f8e401f9e612df2a95c1ef76217c00181389bb5, c712ed63e9b33d9a282fbd92ce25c64918c3129f, 9a8863e8a8def9d88583cd9c60db38a008e6b8cf, 4.17affected
    • 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 and later · before bdf83613781956cc39798ed08321f74ab0467f4daffected · git
    • 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 and later · before 8c4fde01bcf91f22b9c7ded8c3e14addd7ddd500affected · git
    • 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 and later · before ebe2774e956482dd3c70b8991f6f7654356339e6affected · git
    • 0e0c3fee3a59a387aeecc4fca6f3a2e9615a5443 and later · before 9006c116dd111d457bf5d074990210f70a4ad2c8affected · git
    • 3.16.60 and later · before 3.17affected · semver
    • 4.16.6 and later · before 4.17affected · semver
    • before 4.17not affected · semver
    • 6.12.111 and later · up to and including 6.12.*not affected · semver
    • 6.18.53 and later · up to and including 6.18.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.1.10-17.1.10-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan
  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
    40Plan
  • CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux3.17Vendor (CNA)
Linux Linux4.17Vendor (CNA)
Linux Linux8c4fde01bcf91f22b9c7ded8c3e14addd7ddd500Vendor (CNA)
Linux Linux9006c116dd111d457bf5d074990210f70a4ad2c8Vendor (CNA)
Linux Linuxbdf83613781956cc39798ed08321f74ab0467f4dVendor (CNA)
Linux Linuxebe2774e956482dd3c70b8991f6f7654356339e6Vendor (CNA)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

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Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records