CVE-2026-23240: Linux kernel · tls: Fix race condition in tls_sw_cancel_work_tx()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in a5de36d6cee74a92c1a21b260bc507e64bc451de : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:18 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 43% 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 can 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 a5de36d6cee74a92c1a21b260bc507e64bc451de, 17153f154f80be2b47ebf52840f2d8f724eb2f3b, 854cd32bc74fe573353095e90958490e4e4d641b +1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 10 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 Linux kernel to a5de36d6cee74a92c1a21b260bc507e64bc451de, 17153f154f80be2b47ebf52840f2d8f724eb2f3b, 854cd32bc74fe573353095e90958490e4e4d641b or 7bb09315f93dce6acc54bf59e5a95ba7365c2be4.
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– |
AI-suggested
A fix is available and has been applied in the Linux kernel source code as indicated by the fixed commit versions. Users and administrators should update their Linux kernel to a version that includes these fixes to remediate the vulnerability. No alternative mitigations are indicated by the vendor advisory.
Description
CVE-2026-23240 is a critical race condition vulnerability in the Linux kernel's TLS implementation. The issue occurs in the tls_sw_cancel_work_tx() function where a delayed work handler (tx_work_handler) may be scheduled after the TLS object it references has been freed, leading to a use-after-free scenario. This race condition arises because cancel_delayed_work_sync() does not fully prevent the tx_work_handler from being scheduled concurrently from other kernel contexts. The flaw was discovered during a code audit and fixed by replacing cancel_delayed_work_sync() with disable_delayed_work_sync() to properly prevent the race.
References
- git.kernel.org/stable/c/a5de36d6cee74a92c1a21b260bc507e64bc451de (opens in a new tab)
- git.kernel.org/stable/c/854cd32bc74fe573353095e90958490e4e4d641b (opens in a new tab)
- git.kernel.org/stable/c/17153f154f80be2b47ebf52840f2d8f724eb2f3b (opens in a new tab)
- git.kernel.org/stable/c/7bb09315f93dce6acc54bf59e5a95ba7365c2be4 (opens in a new tab)