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NVD / CVE Program· CNA Linux

CVE-2026-68137: net/x25: fix use-after-free in x25_kill_by_neigh()

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.53% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 3f4fe26c20c30bd5a2e2583e80685def0b27858c, 4.10, 4.15; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 3f4fe26c20c30bd5a2e2583e80685def0b27858c, 4.10, 4.15; azl3 kernel 6.6.143.1-1 on Azure Linux 3.0 6.6.150.1-1 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: net/x25: fix use-after-free in x25_kill_by_neigh() x25_kill_by_neigh() walks the global X.25 socket list looking for sockets attached to a terminating neighbour. x25_list_lock protects list membership while the lookup is in progress, but it does not pin a socket's lifetime after the lock is dropped. The function currently drops x25_list_lock before calling lock_sock(s). A concurrent close can run x25_release(), remove the same socket from x25_list, and drop the last socket reference in that window. The neighbour teardown path can then lock or inspect a freed struct sock/struct x25_sock. Take sock_hold(s) while x25_list_lock still proves that the list entry is live, then drop the temporary reference after the socket has been locked, rechecked, and released. Recheck x25_sk(s)->neighbour after lock_sock(), because another path may have disconnected the socket before this path acquired the socket lock. Restart the list walk after each disconnect because the list lock was dropped and the previous iterator state may no longer be valid. A QEMU/KASAN run against origin/master reproduced a slab-use-after-free in x25_kill_by_neigh().

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Aug 10, 2026
Updated
Aug 19, 2026
EPSS
0.5% · 45th percentile
CWE
—

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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When you'll hear from us

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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

    • dffc859d1d9560da594e4282091781b8d2715f00, 858642789ada1b48630f322e59416ca9fca3e6b7, 4c240c5a105557e4546d0836e694868f22fd09b0, 9acf05b4e7b55fdb712ef7b331dbce5bcd391d0f, 4a279d7ee1c65411b4055ecd428b8aa2b1711c1f, 671529db75e6be777bb1c76aa07c2bdd2992be6d, 5.18affected
    • 5c94b6205e87411dbe9dc1ca088eb36b8837fb47 and later · before db6b04f6d65549bb1c7bc8e64a92e7b7d03be676affected · git
    • 409570a619c1cda2e0fde6018a256b9e3d3ba0ee and later · before 5e8a754ac2009a88a7b99ab61eab6296eed360f3affected · git
    • 7781607938c8371d4c2b243527430241c62e39c2 and later · before c98a454d1a9e1bd09d5fd55a7aa589b199340b88affected · git
    • 7781607938c8371d4c2b243527430241c62e39c2 and later · before 3f4fe26c20c30bd5a2e2583e80685def0b27858caffected · git
    • 7781607938c8371d4c2b243527430241c62e39c2 and later · before 610678d4be94b619c751572e8a58de705592cd07affected · git
    • 7781607938c8371d4c2b243527430241c62e39c2 and later · before ec6d91a1bf2ebd767d3d43f6d249ee0ed3f4558aaffected · git
    • 7781607938c8371d4c2b243527430241c62e39c2 and later · before 9aabda553184346f74810e2ee1d96920b4612e3faffected · git
    • 7781607938c8371d4c2b243527430241c62e39c2 and later · before 5499e0602d2faafd42c580d25f615903c3fbe11baffected · git
    • 5.10.110 and later · before 5.10.265affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.101-1~deb12u16.12.101-1~deb12u1
Debian:13linuxbefore 6.12.101-16.12.101-1
Debian:14linuxbefore 7.1.6-17.1.6-1

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-2026-68134Aug 10, 2026 · ptp: ptp_s390: Add missing facility check
    29Monitor
  • ← EarlierCVE-2026-68135Aug 10, 2026 · net: hip04: fix RX buffer leak on build_skb failure
    0Monitor
  • Later →CVE-2026-68147Aug 10, 2026 · fscrypt: Avoid dynamic allocation in fscrypt_get_devices()
    31Monitor

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 Linux3f4fe26c20c30bd5a2e2583e80685def0b27858cVendor (CNA)
Linux Linux4.10Vendor (CNA)
Linux Linux4.15Vendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux5.10.265Vendor (CNA)
Linux Linux5.15.216Vendor (CNA)
Linux Linux5.17Vendor (CNA)
Linux Linux5.18Vendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux5499e0602d2faafd42c580d25f615903c3fbe11bVendor (CNA)
Linux Linux5e8a754ac2009a88a7b99ab61eab6296eed360f3Vendor (CNA)
Linux Linux610678d4be94b619c751572e8a58de705592cd07Vendor (CNA)
Linux Linux9aabda553184346f74810e2ee1d96920b4612e3fVendor (CNA)
Linux Linuxc98a454d1a9e1bd09d5fd55a7aa589b199340b88Vendor (CNA)
Linux Linuxdb6b04f6d65549bb1c7bc8e64a92e7b7d03be676Vendor (CNA)
Linux Linuxec6d91a1bf2ebd767d3d43f6d249ee0ed3f4558aVendor (CNA)
azl3 kernel 6.6.143.1-1 on Azure Linux 3.06.6.150.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.101-1~deb12u1 · Debian:12Package 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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-secondary

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✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

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

All records