CVE-2026-23270: Linux kernel · Use After Free
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.8 High · fixed in fb3c380a54e33d1fd272cc342faa906d787d7ef1 : patch Linux kernel soon.
Data as of 26 Oct 2026, 17:30 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.
- 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, 2026-10-16.
- Patch
- Available – fixed in fb3c380a54e33d1fd272cc342faa906d787d7ef1, bc4e5bb529823a09f02dbe96169de679a9db26e0, 524ce8b4ea8f64900b6c52b6a28df74f6bc0801e +8
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 18 Mar 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
|
| LinuxLinux | Affected
| Fixed in– |
AI-suggested
A fix is available and has been applied in the Linux kernel versions identified by the fixed commits and version numbers. Users should upgrade to these fixed versions to mitigate the vulnerability. No additional mitigation steps are indicated beyond applying the official patches.
Description
CVE-2026-23270 is a high-severity vulnerability in the Linux kernel's network scheduler (net/sched) subsystem. It involves improper binding of the act_ct action to queueing disciplines (qdiscs) other than clsact/ingress and shared blocks, which can lead to use-after-free conditions during packet defragmentation. The flaw was addressed by restricting act_ct binding to only clsact/ingress qdiscs and shared blocks, preventing unsafe usage on egress paths. This vulnerability affects multiple Linux kernel versions prior to the fixed releases.
References
- git.kernel.org/stable/c/bc4e5bb529823a09f02dbe96169de679a9db26e0 (opens in a new tab)
- git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1 (opens in a new tab)
- git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828 (opens in a new tab)
- git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e (opens in a new tab)
- git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6 (opens in a new tab)
- git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4 (opens in a new tab)
- git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)