CVE-2026-63978: Linux kernel · net/handshake: Drain pending requests at net namespace exit
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 19 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| 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
- git.kernel.org/stable/c/ee4b2ba9d30155f9945811cd3c0c1b06d45787a9 (opens in a new tab)
- git.kernel.org/stable/c/9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd (opens in a new tab)
- git.kernel.org/stable/c/2bf24a7e190aae0ea47c78099938ae056c622e44 (opens in a new tab)
- git.kernel.org/stable/c/8c35539db0ab0bfa1ea44efab00b053261a69469 (opens in a new tab)
- git.kernel.org/stable/c/ea5fe6a73ca57e5150b8a38b341aef2636eb72f0 (opens in a new tab)