CVE-2026-64419: Linux kernel · mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-147.147 : update Linux kernel when convenient.
Data as of 30 Oct 2026, 05:37 UTC
- Patch
- Available – fixed in 6.8.0-147.147, 6.8.0-1067.70, 7.0.0-1012.12~24.04.1 +28
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-8726-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8727-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8800-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8917-1 (opens in a new tab)
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 has been released in multiple Linux kernel versions including 6.8.0-147.147 and later. Users and administrators should update to these fixed kernel versions to remediate the issue. No additional mitigation steps are required beyond applying the official kernel updates.
Description
CVE-2026-64419 is a vulnerability in the Linux kernel's memory management subsystem involving the shrinker_debugfs_count_show() function. The issue arises because this function holds an RCU read lock while invoking a callback that may sleep, which is invalid and can cause kernel bugs. The flaw was fixed by removing the unnecessary RCU lock in this context. This vulnerability affects multiple Linux kernel versions prior to the fixed releases.
References
- ubuntu.com/security/CVE-2026-64419 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-64419 (opens in a new tab)
- git.kernel.org/linus/b902890c62d200b3509cb5e09cf1e0a66553c128 (opens in a new tab)
- git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4 (opens in a new tab)
- git.kernel.org/stable/c/560e21e8ccff813e84d05f6500907c549a3d6985 (opens in a new tab)
- git.kernel.org/stable/c/86237e56091e70f09c0fbf217f9d9c0e08f556c4 (opens in a new tab)
- git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128 (opens in a new tab)
- git.kernel.org/stable/c/de5f69b8dae8698ac5e48dfcd30017887cdf4e5a (opens in a new tab)
- git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8727-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8800-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8760-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8726-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8728-3 (opens in a new tab)