CVE-2025-21834: Linux kernel · seccomp: passthrough uretprobe systemcall without filtering
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 6.11.0-21.21~24.04.1 : update Linux kernel when convenient.
Data as of 29 Oct 2026, 23:41 UTC
- Patch
- Available – fixed in 6.11.0-21.21~24.04.1, 6.11.0-1017.17
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 6 Mar 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 Oct 2026.
What to do
Upgrade the Ubuntu to 6.11.0-21.21~24.04.1 (linux-hwe-6.11 package) or 6.11.0-1017.17 (linux-oem-6.11 package).
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinux-hwe-6.11pkg:deb/ubuntu/linux-hwe-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-oem-6.11pkg:deb/ubuntu/linux-oem-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-raspi-realtimepkg:deb/ubuntu/linux-raspi-realtime?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-allwinner-5.19pkg:deb/ubuntu/linux-allwinner-5.19?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-aws-5.19pkg:deb/ubuntu/linux-aws-5.19?arch=source&distro=jammyOther threats | Affected
| Fixed in– |
Ubuntu 22.04 LTSlinux-aws-6.2pkg:deb/ubuntu/linux-aws-6.2?arch=source&distro=jammyOther 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 included in Linux kernel versions 6.11.0-21.21~24.04.1, 6.11.0-1017.17, and later. Users should update to these fixed kernel versions to resolve the issue. Since the fix allows the uretprobe syscall to pass through seccomp filters unconditionally, no additional configuration changes are required. No other mitigation actions are necessary.
Description
A vulnerability in the Linux kernel seccomp subsystem allowed the passthrough of the uretprobe system call without filtering. This caused processes running inside Docker or other userspace applications using seccomp to segfault when encountering the uretprobe return probe, as the default seccomp filters blocked this syscall. The issue arises because uretprobe is a kernel implementation detail not typically allowed by default in seccomp filters. The vulnerability has been fixed by allowing this syscall to pass through seccomp unconditionally. The fix is included in Linux kernel versions 6.11.0-21.21~24.04.1 and 6.11.0-1017.17 and later.
References
- ubuntu.com/security/CVE-2025-21834 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-21834 (opens in a new tab)
- git.kernel.org/linus/cf6cb56ef24410fb5308f9655087f1eddf4452e6 (opens in a new tab)
- git.kernel.org/stable/c/5a262628f4cf2437d863fe41f9d427177b87664c (opens in a new tab)
- git.kernel.org/stable/c/cf6cb56ef24410fb5308f9655087f1eddf4452e6 (opens in a new tab)
- git.kernel.org/stable/c/fa80018aa5be10c35e9fa896b7b4061a8dce3eed (opens in a new tab)
- ubuntu.com/security/notices/USN-7379-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7380-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7381-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7382-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7379-2 (opens in a new tab)