Skip to main content
VulnerabilityPublished Updated

CVE-2026-63978: Linux kernel · net/handshake: Drain pending requests at net namespace exit

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical · fixed in ee4b2ba9d30155f9945811cd3c0c1b06d45787a9 : patch Linux kernel as a priority.

Data as of 26 Oct 2026, 21:18 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers can reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in ee4b2ba9d30155f9945811cd3c0c1b06d45787a9, ea5fe6a73ca57e5150b8a38b341aef2636eb72f0, 9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd +2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 3b3009ea8abb713b022d94fba95ec270cf6e7eae, < ee4b2ba9d30155f9945811cd3c0c1b06d45787a9
Fixed in
  • ee4b2ba9d30155f9945811cd3c0c1b06d45787a9
LinuxLinuxAffected
  • ≥ 3b3009ea8abb713b022d94fba95ec270cf6e7eae, < ea5fe6a73ca57e5150b8a38b341aef2636eb72f0
Fixed in
  • ea5fe6a73ca57e5150b8a38b341aef2636eb72f0
LinuxLinuxAffected
  • ≥ 3b3009ea8abb713b022d94fba95ec270cf6e7eae, < 9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd
Fixed in
  • 9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd
LinuxLinuxAffected
  • ≥ 3b3009ea8abb713b022d94fba95ec270cf6e7eae, < 8c35539db0ab0bfa1ea44efab00b053261a69469
Fixed in
  • 8c35539db0ab0bfa1ea44efab00b053261a69469
LinuxLinuxAffected
  • ≥ 3b3009ea8abb713b022d94fba95ec270cf6e7eae, < 2bf24a7e190aae0ea47c78099938ae056c622e44
Fixed in
  • 2bf24a7e190aae0ea47c78099938ae056c622e44
LinuxLinuxAffected
  • =6.4
Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel. Users should update to the fixed versions identified by the commits (ee4b2ba9d30155f9945811cd3c0c1b06d45787a9, ea5fe6a73ca57e5150b8a38b341aef2636eb72f0, 9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd, 8c35539db0ab0bfa1ea44efab00b053261a69469, 2bf24a7e190aae0ea47c78099938ae056c622e44) to remediate this issue. No additional mitigations are indicated beyond applying the official patch.

Description

CVE-2026-63978 is a critical vulnerability in the Linux kernel's network handshake code where pending handshake requests are not properly drained when a network namespace exits. This occurs due to reversed arguments in a list_splice_init() call, causing the drain loop to skip pending requests. The fix corrects the splice direction and adds safeguards to prevent list corruption races during concurrent cancellation and draining of handshake requests.

References

Community reviews

Loading reviews…