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CVE-2026-89766— pidfd: hold exec_update_lock around namespace ioctl

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.11版本存在安全漏洞，该漏洞源于pidfd_ioctl()中的PIDFD_GET_*_NAMESPACE ioctl在执行文件系统凭据ptrace访问检查时未持有目标任务的exec_update_lock，可能导致攻击者在对目标旧凭据检查通过后读取命名空间，访问本应被拒绝的命名空间信息。

AI Predicted 4.4 Difficulty: Moderate EPSS 0.21% · P10

Possible ATT&CK Techniques 1 AI

T1132 · Data Encoding

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12< bac2f1913a216677c2c220d7bb352dd0330065ca affected
5b08bd408534bfb3a7cf5778da5b27d4e4fffe12< cf24ce48d60225fdbee68ed2058763a1fd172ff3 affected
5b08bd408534bfb3a7cf5778da5b27d4e4fffe12< e89318aa8629969e86548b05e7c19283af3f0efb affected
5b08bd408534bfb3a7cf5778da5b27d4e4fffe12< 9688a46802939da28f00cb40e8129615d5d4af39 affected
6.11 affected
< 6.11 unaffected
6.12.112≤ 6.12.* unaffected
6.18.51≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-89766

Vulnerability Information
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Vulnerability Title
pidfd: hold exec_update_lock around namespace ioctl
Source: CVE Program / CVE List V5
Vulnerability Description
In 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.11版本存在安全漏洞，该漏洞源于pidfd_ioctl()中的PIDFD_GET_*_NAMESPACE ioctl在执行文件系统凭据ptrace访问检查时未持有目标任务的exec_update_lock，可能导致攻击者在对目标旧凭据检查通过后读取命名空间，访问本应被拒绝的命名空间信息。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 5b08bd408534bfb3a7cf5778da5b27d4e4fffe12 ~ bac2f1913a216677c2c220d7bb352dd0330065ca -
Linux Linux 6.11 -

II. Public POCs for CVE-2026-89766

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III. Intelligence Information for CVE-2026-89766

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Patches & Fixes for CVE-2026-89766 (4)

Same Patch Batch · Linux · 2026-09-11 · 431 CVEs total

CVE-2026-89669 9.8 CRITICAL nfsd: initialize copy-notify stateid before publishing it
CVE-2026-89536 9.8 CRITICAL SUNRPC: wait for in-flight client TLS handshake callback
CVE-2026-89533 9.8 CRITICAL svcrdma: Fix offset arithmetic in read_chunk_range
CVE-2026-81002 9.8 CRITICAL xdp: fix zero-copy frame layout
CVE-2026-89643 9.8 CRITICAL audit: avoid dropping live tree ref on fsnotify rule autoremove
CVE-2026-89526 9.8 CRITICAL svcrdma: Validate Read chunk positions before reconstruction
CVE-2026-89652 9.8 CRITICAL ceph: bound copied dentry name length in NFS export get_name
CVE-2026-89651 9.8 CRITICAL ceph: bound MDSCapAuth path and fs_name decode in handle_session()
CVE-2026-89653 9.8 CRITICAL ceph: reject export_targets ranks >= CEPH_MAX_MDS in mdsmap decode
CVE-2026-89654 9.8 CRITICAL ceph: fix UAF in check_new_map() on session freed during unlock
CVE-2026-89656 9.8 CRITICAL libceph: reject buckets with mismatched CRUSH ids
CVE-2026-89655 9.8 CRITICAL ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock
CVE-2026-89712 9.8 CRITICAL NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock
CVE-2026-89658 9.8 CRITICAL NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup
CVE-2026-89660 9.8 CRITICAL NFSD: Prevent client use-after-free during admin state revocation
CVE-2026-89659 9.8 CRITICAL NFSD: Prevent client use-after-free during delegation revoke
CVE-2026-89708 9.8 CRITICAL nfsd: RCU-protect cl_cb_session to fix use-after-free on session teardown
CVE-2026-89662 9.8 CRITICAL NFSD: Prevent lock owner use-after-free during client teardown
CVE-2026-89689 9.8 CRITICAL nfsd: don't free session slots that are still in use
CVE-2026-89686 9.8 CRITICAL nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke

Showing top 20 of 431 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-89766

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