{"id":"CVE-2026-89766","title":"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 handi…","summary":"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 handi…","severity":"high","cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-367"],"vendor":"Linux","product":"Linux","affected":["Linux >= 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 < bac2f1913a216677c2c220d7bb352dd0330065ca","Linux >= 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 < cf24ce48d60225fdbee68ed2058763a1fd172ff3","Linux >= 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 < e89318aa8629969e86548b05e7c19283af3f0efb","Linux >= 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 < 9688a46802939da28f00cb40e8129615d5d4af39","Linux 6.11"],"published":"2026-09-11","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:17:43.130","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-89766","references":[{"url":"https://git.kernel.org/stable/c/9688a46802939da28f00cb40e8129615d5d4af39","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bac2f1913a216677c2c220d7bb352dd0330065ca","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cf24ce48d60225fdbee68ed2058763a1fd172ff3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e89318aa8629969e86548b05e7c19283af3f0efb","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89766.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89766"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532287"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89766"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89766"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89766.mbox"},{"url":"https://kernelcve.org/list/?q=CVE-2026-89766"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00191,"epssPercentile":0.08731,"cvssSource":"vendor","ingestedAt":"2026-09-14T11:11:19.884Z","slug":"CVE-2026-89766","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89766.json)","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":208932,"id":"CVE-2026-89766","ts":1790062293541,"field":"cvss","old":"2.5","new":"7"},{"seq":208931,"id":"CVE-2026-89766","ts":1790062293541,"field":"severity","old":"low","new":"high"},{"seq":204017,"id":"CVE-2026-89766","ts":1789490231064,"field":"cvss","old":null,"new":"2.5"},{"seq":204016,"id":"CVE-2026-89766","ts":1789490231064,"field":"severity","old":"none","new":"low"},{"seq":147406,"id":"CVE-2026-89766","ts":1789270210786,"field":"cvss","old":null,"new":"2.5"},{"seq":147405,"id":"CVE-2026-89766","ts":1789270210786,"field":"severity","old":"none","new":"low"},{"seq":109166,"id":"CVE-2026-89766","ts":1789183730570,"field":"cvss","old":null,"new":"2.5"},{"seq":109165,"id":"CVE-2026-89766","ts":1789183730570,"field":"severity","old":"none","new":"low"}]}