CVE-2026-23105: Linux kernel · Improper Input Validation
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.8 High · fixed in fac2c67bb2bb732eae4283e45fc338af7e08c254 : patch Linux kernel soon.
Data as of 26 Oct 2026, 17:16 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.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-06-16.
- Patch
- Available – fixed in fac2c67bb2bb732eae4283e45fc338af7e08c254, f27047abf7cac1b6f90c3ad60de21ef9f717c26d, d837fbee92453fbb829f950c8e7cf76207d73f33 +4
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 |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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AI-suggested
A fix is available and has been applied in specific commits to the Linux kernel source. Users and administrators should update their Linux kernel to a version that includes these fixes to mitigate this vulnerability. Since this is not a cloud service, manual patching is required. There is no indication that additional mitigation steps are necessary beyond applying the official fix.
Description
CVE-2026-23105 is a high-severity vulnerability in the Linux kernel's net/sched subsystem affecting version 3.8. It involves improper determination of class activation in the qfq scheduler, where reliance on the child qdisc's queue length could be manipulated. The issue was fixed by using the cl_is_active function to more reliably check class activity, preventing potential exploits related to child queue length manipulation.
References
- git.kernel.org/stable/c/fac2c67bb2bb732eae4283e45fc338af7e08c254 (opens in a new tab)
- git.kernel.org/stable/c/b8c24cf5268fb3bfb8d16324c3dbb985f698c835 (opens in a new tab)
- git.kernel.org/stable/c/f27047abf7cac1b6f90c3ad60de21ef9f717c26d (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/77f1afd0bb4d5da95236f6114e6d0dfcde187ff6 (opens in a new tab)
- git.kernel.org/stable/c/d837fbee92453fbb829f950c8e7cf76207d73f33 (opens in a new tab)