{"id":"CVE-2026-89766","state":"PUBLISHED","title":"pidfd: hold exec_update_lock around namespace ioctl","description":"In the Linux kernel, the following vulnerability has been resolved:\n\npidfd: hold exec_update_lock around namespace ioctl\n\nThe PIDFD_GET_*_NAMESPACE ioctls in pidfd_ioctl() perform a filesystem\ncredentials ptrace access check before handing out a namespace file\ndescriptor.  The accompanying comment states that the code \"mirrors nsfs\nbehavior\", but, unlike the corresponding procfs paths, it does so without\nholding the target task's exec_update_lock.\n\nproc_ns_get_link() and proc_ns_readlink() both take exec_update_lock for\nreading around the ptrace check and the namespace lookup, so that the\ncredentials used for the access decision match those of the task when its\nnamespace is read.  Without it, a caller can pass the check against the\ntarget's old credentials and then read the namespace after the target has\nexecve()'d a setuid binary and committed new credentials -- accessing\nnamespace information it should have been denied.\n\nHold exec_update_lock for reading around the ptrace check and the\nnamespace lookup so that pidfd truly mirrors nsfs behavior, as the comment\nalready claims.  open_namespace() itself runs outside the lock: once a\nnamespace reference is obtained it carries its own refcount and is opened\nwith the caller's own credentials, so a concurrent execve() on the target\ncan no longer affect the outcome.","publishedAt":"2026-09-11T19:47:06.597Z","updatedAt":"2026-10-19T08:52:19.816Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"bac2f1913a216677c2c220d7bb352dd0330065ca","versionType":"git"},{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"cf24ce48d60225fdbee68ed2058763a1fd172ff3","versionType":"git"},{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"e89318aa8629969e86548b05e7c19283af3f0efb","versionType":"git"},{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"9688a46802939da28f00cb40e8129615d5d4af39","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/pidfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/pidfs.c"]}],"references":["https://git.kernel.org/stable/c/bac2f1913a216677c2c220d7bb352dd0330065ca","https://git.kernel.org/stable/c/cf24ce48d60225fdbee68ed2058763a1fd172ff3","https://git.kernel.org/stable/c/e89318aa8629969e86548b05e7c19283af3f0efb","https://git.kernel.org/stable/c/9688a46802939da28f00cb40e8129615d5d4af39"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/89xxx/CVE-2026-89766.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89766","state":"PUBLISHED","datePublished":"2026-09-11T19:47:06.597Z","dateUpdated":"2026-10-19T08:52:19.816Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.764Z"},"containers":{"cna":{"title":"pidfd: hold exec_update_lock around namespace ioctl","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\npidfd: hold exec_update_lock around namespace ioctl\n\nThe PIDFD_GET_*_NAMESPACE ioctls in pidfd_ioctl() perform a filesystem\ncredentials ptrace access check before handing out a namespace file\ndescriptor.  The accompanying comment states that the code \"mirrors nsfs\nbehavior\", but, unlike the corresponding procfs paths, it does so without\nholding the target task's exec_update_lock.\n\nproc_ns_get_link() and proc_ns_readlink() both take exec_update_lock for\nreading around the ptrace check and the namespace lookup, so that the\ncredentials used for the access decision match those of the task when its\nnamespace is read.  Without it, a caller can pass the check against the\ntarget's old credentials and then read the namespace after the target has\nexecve()'d a setuid binary and committed new credentials -- accessing\nnamespace information it should have been denied.\n\nHold exec_update_lock for reading around the ptrace check and the\nnamespace lookup so that pidfd truly mirrors nsfs behavior, as the comment\nalready claims.  open_namespace() itself runs outside the lock: once a\nnamespace reference is obtained it carries its own refcount and is opened\nwith the caller's own credentials, so a concurrent execve() on the target\ncan no longer affect the outcome."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"bac2f1913a216677c2c220d7bb352dd0330065ca","versionType":"git"},{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"cf24ce48d60225fdbee68ed2058763a1fd172ff3","versionType":"git"},{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"e89318aa8629969e86548b05e7c19283af3f0efb","versionType":"git"},{"version":"5b08bd408534bfb3a7cf5778da5b27d4e4fffe12","status":"affected","lessThan":"9688a46802939da28f00cb40e8129615d5d4af39","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/pidfs.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.51","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.4","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/pidfs.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/bac2f1913a216677c2c220d7bb352dd0330065ca"},{"url":"https://git.kernel.org/stable/c/cf24ce48d60225fdbee68ed2058763a1fd172ff3"},{"url":"https://git.kernel.org/stable/c/e89318aa8629969e86548b05e7c19283af3f0efb"},{"url":"https://git.kernel.org/stable/c/9688a46802939da28f00cb40e8129615d5d4af39"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T08:52:19.816Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.18.51"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}