CVE-2025-68809: Linux kernel · ksmbd: vfs: fix race on m_flags in vfs_cache
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.1 Critical · fixed in 6.8.0-1052.55~22.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1052.55~22.04.1, 6.8.0-1059.65~22.04.1, 6.8.0-1058.65~22.04.1 +43
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 Jan 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 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther 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
An official fix is available and should be applied. The vulnerability is resolved by updating the Linux kernel to a version that includes the patch unifying locking around m_flags in ksmbd. After updating, a system reboot is required to apply the changes. No additional mitigation steps are necessary as the patch fully addresses the race condition.
Description
A race condition vulnerability in the Linux kernel's ksmbd component was fixed. The issue involved inconsistent locking around the m_flags field in vfs_cache, leading to potential data races when multiple threads concurrently open, close, and delete the same file. This could cause incorrect delete-on-close and pending-delete behavior, such as files not being deleted as expected or disappearing prematurely. The fix unified locking around m_flags to prevent these race conditions.
References
- ubuntu.com/security/CVE-2025-68809 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-68809 (opens in a new tab)
- git.kernel.org/linus/991f8a79db99b14c48d20d2052c82d65b9186cad (opens in a new tab)
- git.kernel.org/stable/c/5adad9727a815c26013b0d41cfee92ffa7d4037c (opens in a new tab)
- git.kernel.org/stable/c/991f8a79db99b14c48d20d2052c82d65b9186cad (opens in a new tab)
- git.kernel.org/stable/c/ccc78781041589ea383e61d5d7a1e9a31b210b93 (opens in a new tab)
- git.kernel.org/stable/c/ee63729760f5b61a66f345c54dc4c7514e62383d (opens in a new tab)
- ubuntu.com/security/notices/USN-8177-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8177-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8183-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8184-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8185-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8183-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8203-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8204-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8185-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-4 (opens in a new tab)