CVE-2026-23168: Linux kernel · flex_proportions: make fprop_new_period() hardirq safe
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1057.60~22.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 6.8.0-1057.60~22.04.1, 6.8.0-1059.65~22.04.1, 6.8.0-1058.65~22.04.1 +37
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 14 Feb 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
A vendor-provided patch is available and should be applied to affected Linux kernel versions. The Ubuntu security advisory USN-8278-1 provides updates that fix this and other kernel vulnerabilities. Systems running the affected versions should be updated promptly to prevent potential deadlocks. No additional mitigation actions are indicated by the vendor advisory.
Description
A vulnerability in the Linux kernel's flexible proportions (flex_proportions) code could cause a deadlock due to a race condition involving sequence counters in hardirq and softirq contexts. This issue arises when the block device interface (bdi) is configured with a maximum fraction of writeout throughput, which is uncommon but frequent in certain configurations like FUSE bdis. The vulnerability has been fixed by making the write section of the sequence counter interrupt-safe. The issue affects specific Linux kernel versions and has a medium severity rating with a CVSS score of 5.5. A patch is available from the vendor.
References
- ubuntu.com/security/CVE-2026-23168 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23168 (opens in a new tab)
- git.kernel.org/linus/dd9e2f5b38f1fdd49b1ab6d3a85f81c14369eacc (opens in a new tab)
- git.kernel.org/stable/c/0acc9ba7a1b5ba4d998c5753e709be904e179b75 (opens in a new tab)
- git.kernel.org/stable/c/78ede9ebd679dadf480dce6f7b798e3603f88348 (opens in a new tab)
- git.kernel.org/stable/c/884b2590ffcc7222cbbd6298051f4c243cc36f5d (opens in a new tab)
- git.kernel.org/stable/c/b91a84299d72ae0e05551e851e47cd3008bd025b (opens in a new tab)
- git.kernel.org/stable/c/dd9e2f5b38f1fdd49b1ab6d3a85f81c14369eacc (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8296-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8296-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8393-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8440-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8499-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8570-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8594-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8604-1 (opens in a new tab)