CVE-2026-23105: Linux kernel · net/sched: qfq: Use cl_is_active to determine whether class is active in qfq_rm_from_ag
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1105.112~20.04.1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 16:04 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 3% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1105.112~20.04.1, 5.15.0-1110.119~20.04.1, 5.15.0-1106.115~20.04.1 +70
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 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 patch is available and has been released by Ubuntu in updated Linux kernel packages for affected versions. Users should apply the standard system updates and reboot their systems to ensure the vulnerability is remediated. Due to an ABI change in the kernel update, recompilation and reinstallation of any third-party kernel modules are required. Follow vendor instructions carefully to complete the update process.
Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: qfq: Use cl_is_active to determine whether class is active in qfq_rm_from_ag This is more of a preventive patch to make the code more consistent and to prevent possible exploits that employ child qlen manipulations on qfq. use cl_is_active instead of relying on the child qdisc's qlen to determine class activation.
References
- ubuntu.com/security/CVE-2026-23105 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23105 (opens in a new tab)
- git.kernel.org/linus/d837fbee92453fbb829f950c8e7cf76207d73f33 (opens in a new tab)
- git.kernel.org/stable/c/77f1afd0bb4d5da95236f6114e6d0dfcde187ff6 (opens in a new tab)
- git.kernel.org/stable/c/93b8635974fb050c43d07e35e5edfe6e685ca28a (opens in a new tab)
- git.kernel.org/stable/c/abd9fc26ea577561a5ef6241a1b058755ffdad0c (opens in a new tab)
- git.kernel.org/stable/c/d837fbee92453fbb829f950c8e7cf76207d73f33 (opens in a new tab)
- ubuntu.com/security/notices/USN-8162-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8180-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8180-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8186-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8187-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8188-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8180-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8180-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8180-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-8243-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8180-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-8275-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-1 (opens in a new tab)