pidfd: hold exec_update_lock around namespace ioctl

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89766
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:20:07 UTC
Updated2026-09-11 20:20:07 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: pidfd: hold exec_update_lock around namespace ioctl The PIDFD_GET_*_NAMESPACE ioctls in pidfd_ioctl() perform a filesystem credentials ptrace access check before handing out a namespace file descriptor. The accompanying comment states that the code "mirrors nsfs behavior", but, unlike the corresponding procfs paths, it does so without holding the target task's exec_update_lock. proc_ns_get_link() and proc_ns_readlink() both take exec_update_lock for reading around the ptrace check and the namespace lookup, so that the credentials used for the access decision match those of the task when its namespace is read. Without it, a caller can pass the check against the target's old credentials and then read the namespace after the target has execve()'d a setuid binary and committed new credentials -- accessing namespace information it should have been denied. Hold exec_update_lock for reading around the ptrace check and the namespace lookup so that pidfd truly mirrors nsfs behavior, as the comment already claims. open_namespace() itself runs outside the lock: once a namespace reference is obtained it carries its own refcount and is opened with the caller's own credentials, so a concurrent execve() on the target can no longer affect the outcome.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 cf24ce48d60225fdbee68ed2058763a1fd172ff3 git Not specified
CNA Linux Linux affected 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 e89318aa8629969e86548b05e7c19283af3f0efb git Not specified
CNA Linux Linux affected 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 9688a46802939da28f00cb40e8129615d5d4af39 git Not specified
CNA Linux Linux affected 6.11 Not specified
CNA Linux Linux unaffected 6.11 semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/e89318aa8629969e86548b05e7c19283af3f0efb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/cf24ce48d60225fdbee68ed2058763a1fd172ff3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9688a46802939da28f00cb40e8129615d5d4af39 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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