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NVD / CVE Program· CNA Linux

CVE-2025-40256: xfrm: also call xfrm_state_delete_tunnel at destroy time for states that were never added

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.20% (FIRST EPSS).
  • Fixed version: Linux Linux 10deb69864840ccf96b00ac2ab3a2055c0c04721, 1dad653643f28ccc89be93f9440b8804cded85b2, 57b72d74d4651dc19d046308a8304eb9abfe66ac.

Low priority for now. Upgrade to Linux Linux 10deb69864840ccf96b00ac2ab3a2055c0c04721, 1dad653643f28ccc89be93f9440b8804cded85b2, 57b72d74d4651dc19d046308a8304eb9abfe66ac or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: xfrm: also call xfrm_state_delete_tunnel at destroy time for states that were never added In commit b441cf3f8c4b ("xfrm: delete x->tunnel as we delete x"), I missed the case where state creation fails between full initialization (->init_state has been called) and being inserted on the lists. In this situation, ->init_state has been called, so for IPcomp tunnels, the fallback tunnel has been created and added onto the lists, but the user state never gets added, because we fail before that. The user state doesn't go through __xfrm_state_delete, so we don't call xfrm_state_delete_tunnel for those states, and we end up leaking the FB tunnel. There are several codepaths affected by this: the add/update paths, in both net/key and xfrm, and the migrate code (xfrm_migrate, xfrm_state_migrate). A "proper" rollback of the init_state work would probably be doable in the add/update code, but for migrate it gets more complicated as multiple states may be involved. At some point, the new (not-inserted) state will be destroyed, so call xfrm_state_delete_tunnel during xfrm_state_gc_destroy. Most states will have their fallback tunnel cleaned up during __xfrm_state_delete, which solves the issue that b441cf3f8c4b (and other patches before it) aimed at. All states (including FB tunnels) will be removed from the lists once xfrm_state_fini has called flush_work(&xfrm_state_gc_work).

—No exploit Fix available
Published
Dec 4, 2025
Updated
Oct 19, 2026
EPSS
0.2% · 10th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

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

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

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

    • 6.16affected
    • 1b28a7fae0128fa140a7dccd995182ff6cd1c67b and later · before 57b72d74d4651dc19d046308a8304eb9abfe66acaffected · git
    • 4b2c17d0f9be8b58bb30468bc81a4b61c985b04e and later · before 1dad653643f28ccc89be93f9440b8804cded85b2affected · git
    • 0da961fa46da1b37ef868d9b603bd202136f8f8e and later · before 64441724387b4ac92f67ef51caaaeffe99c950d1affected · git
    • d0e0d1097118461463b76562c7ebaabaa5b90b13 and later · before 763e5c351206c1e4d910db4a1159053f6263689caffected · git
    • dc3636912d41770466543623cb76e7b88fdb42c7 and later · before f7d879c19d306512c2e260f37e8a3e5c85e37c50affected · git
    • b441cf3f8c4b8576639d20c8eb4aa32917602ecd and later · before d6fe5c740c573af10943b8353992e1325cdb2715affected · git
    • b441cf3f8c4b8576639d20c8eb4aa32917602ecd and later · before 10deb69864840ccf96b00ac2ab3a2055c0c04721affected · git
    • before 6.16not affected · semver
    • 6.17.10 and later · up to and including 6.17.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:14linuxbefore 6.17.10-16.17.10-1

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

Published before and after this one in the same product

  • ← EarlierCVE-2025-40254Dec 4, 2025 · net: openvswitch: remove never-working support for setting nsh fields
    0Monitor
  • ← EarlierCVE-2025-40255Dec 4, 2025 · net: core: prevent NULL deref in generic_hwtstamp_ioctl_lower()
    0Monitor
  • Later →CVE-2025-40257Dec 4, 2025 · mptcp: fix a race in mptcp_pm_del_add_timer()
    39Monitor

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 Linux10deb69864840ccf96b00ac2ab3a2055c0c04721Vendor (CNA)
Linux Linux1dad653643f28ccc89be93f9440b8804cded85b2Vendor (CNA)
Linux Linux57b72d74d4651dc19d046308a8304eb9abfe66acVendor (CNA)
Linux Linux64441724387b4ac92f67ef51caaaeffe99c950d1Vendor (CNA)
Linux Linux763e5c351206c1e4d910db4a1159053f6263689cVendor (CNA)
Linux Linuxd6fe5c740c573af10943b8353992e1325cdb2715Vendor (CNA)
Linux Linuxf7d879c19d306512c2e260f37e8a3e5c85e37c50Vendor (CNA)
debian:linux6.17.10-1 · Debian:14Package 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

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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.

—

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)

—

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

Show all references (6 more)

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

All records