CVE-2026-64523: Linux kernel · net/handshake: Take a long-lived file reference at submit
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 7.0.0-28.28~24.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 7.0.0-28.28~24.04.1, 7.0.0-1016.16~24.04.1, 6.8.0-1035.38 +12
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 25 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 |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available and should be applied to affected Linux kernel versions. The vendor advisory from Ubuntu confirms that this issue has been fixed. Users should update their Linux kernel packages to the fixed versions as per their distribution's security notices. No additional mitigation steps are required beyond applying the official patch.
Description
A critical vulnerability in the Linux kernel's net/handshake subsystem was resolved, involving improper management of file references during handshake request submission. The flaw could lead to premature socket teardown due to missing file pointer references, potentially causing system instability or exploitation. The issue was fixed by adding explicit file reference handling and synchronization to prevent race conditions. This vulnerability has a CVSS score of 9.8, indicating critical severity. Multiple Linux kernel versions are affected, and patches are available.
References
- ubuntu.com/security/CVE-2026-64523 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-64523 (opens in a new tab)
- git.kernel.org/linus/09dba37eee70d0596e26645015f1aa95a9848e9d (opens in a new tab)
- git.kernel.org/stable/c/09dba37eee70d0596e26645015f1aa95a9848e9d (opens in a new tab)
- git.kernel.org/stable/c/16eaba5aa89c04eea125905bb8f988c1897f4f29 (opens in a new tab)
- git.kernel.org/stable/c/685b10dd0e32c7782cead16c8cf055c609678583 (opens in a new tab)
- ubuntu.com/security/notices/USN-8618-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8663-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8664-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8781-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)