CVE-2025-21834: seccomp: passthrough uretprobe systemcall without filtering

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-03-06 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: seccomp: passthrough uretprobe systemcall without filtering When attaching uretprobes to processes running inside docker, the attached process is segfaulted when encountering the retprobe. The reason is that now that uretprobe is a system call the default seccomp filters in docker block it as they only allow a specific set of known syscalls. This is true for other userspace applications which use seccomp to control their syscall surface. Since uretprobe is a "kernel implementation detail" system call which is not used by userspace application code directly, it is impractical and there's very little point in forcing all userspace applications to explicitly allow it in order to avoid crashing tracked processes. Pass this systemcall through seccomp without depending on configuration. Note: uretprobe is currently only x86_64 and isn't expected to ever be supported in i386. [kees: minimized changes for easier backporting, tweaked commit log]

Affected products

Linux kernel: from 6.11 before 6.12.14; from 6.13 before 6.13.3; 6.14-rc1 — fixed in 6.12.14, 6.13.3

How to fix

Upgrade to a fixed version: Linux kernel 6.12.14, 6.13.3. Check the vendor advisory for mitigations.

References

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