CVE-2025-68756: Linux kernel · block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock
Affects Linux kernelSource GCVE Database
Not known to be exploited · fixed in 6.8.0-1052.55~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% 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, 6.8.0-1054.57~22.04.1 +40
Exploitation evidence
Disclosed: evidence found.
CVE published 5 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@6.17.0-19.19?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1009.9?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1010.10?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1009.9?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1009.9?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
A patch is available and should be applied to affected Linux kernel versions to resolve the deadlock issue. The fix replaces mutex locking with RCU mechanisms in the relevant block layer functions. Users should update to the patched kernel versions as provided by their distribution vendor. No additional mitigation is required beyond applying the official fix.
Description
A deadlock vulnerability in the Linux kernel block layer was resolved by changing the synchronization method from mutex locking to RCU in blk_mq_[un]quiesce_tagset() and related functions. The issue caused deadlocks during NVMe device timeout handling when the kernel tried to quiesce tagsets while holding a mutex that was also needed by other threads. This fix prevents the deadlock by using RCU-safe list operations instead of mutex locks. The vulnerability affects specific Linux kernel versions used in the linux-hwe-edge package. A patch is available to address this issue.
References
- ubuntu.com/security/CVE-2025-68756 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-68756 (opens in a new tab)
- git.kernel.org/linus/59e25ef2b413c72da6686d431e7759302cfccafa (opens in a new tab)
- git.kernel.org/stable/c/3baeec23a82e7ee9691f434c6ab0ab1387326108 (opens in a new tab)
- git.kernel.org/stable/c/59e25ef2b413c72da6686d431e7759302cfccafa (opens in a new tab)
- git.kernel.org/stable/c/6e8d363786765a81e35083e0909e076796468edf (opens in a new tab)
- git.kernel.org/stable/c/ef0cd7b694928573f6569e61c14f5f059253162e (opens in a new tab)
- ubuntu.com/security/notices/USN-8094-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8094-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8094-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8094-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8094-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8152-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8179-1 (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-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)