CVE-2026-31533: Linux kernel · net/tls: fix use-after-free in -EBUSY error path of tls_do_encryption
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 9.8 Critical · fixed in 5.4.0-1160.170~18.04.1 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 33% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.4.0-1160.170~18.04.1, 5.4.0-1163.169~18.04.1, 5.4.0-1162.171~18.04.1 +96
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 23 Apr 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 26.04 LTSlinux-nvidiapkg:deb/ubuntu/linux-nvidia@7.0.0-1006.6?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-29.29?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1015.15?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1015.15?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1018.19?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 should be applied promptly. The vendor advisory from Ubuntu confirms that this issue is fixed in updated Linux kernel packages. After applying the update, a system reboot is required. Due to ABI changes, third-party kernel modules must be recompiled and reinstalled. Follow vendor instructions for updating to the fixed kernel versions.
Description
A use-after-free vulnerability in the Linux kernel's TLS encryption code (tls_do_encryption) was fixed. The flaw involves double cleanup of encryption-related data structures when handling -EBUSY errors, leading to memory corruption and potential use-after-free conditions. This vulnerability affects specific Linux kernel versions and has a high CVSS score of 9.8. A patch is available and should be applied to mitigate the issue.
References
- ubuntu.com/security/CVE-2026-31533 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-31533 (opens in a new tab)
- git.kernel.org/linus/a9b8b18364fffce4c451e6f6fd218fa4ab646705 (opens in a new tab)
- ubuntu.com/security/notices/USN-8277-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8279-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8280-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8277-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8279-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8280-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8279-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8289-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8305-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8278-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8280-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8305-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8310-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8350-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8351-1 (opens in a new tab)