CyberSecBulletin
CVE-2026-46274NVD status: Analyzed

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-46274 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions d6bda9df0c0a3080804181464d5c0f4d78a4e769, 5a20ebf0c81b61f5ea3b1b529c100cad69b9f603, 252c5051dba9c709b6a72f2866f93e5e618b3f06 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to d6bda9df0c0a3080804181464d5c0f4d78a4e769 or 5a20ebf0c81b61f5ea3b1b529c100cad69b9f603 or 252c5051dba9c709b6a72f2866f93e5e618b3f06 or d376c131af7c7739a87ff037ed2fdb67c2542c8a, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.9 or 6.6.141 or 6.12.91 or 6.18.33, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux204361a77f4018627addd4a06877448f088ddfc0 up to, but not including, d6bda9df0c0a3080804181464d5c0f4d78a4e769; 204361a77f4018627addd4a06877448f088ddfc0 up to, but not including, 5a20ebf0c81b61f5ea3b1b529c100cad69b9f603; 204361a77f4018627addd4a06877448f088ddfc0 up to, but not including, 252c5051dba9c709b6a72f2866f93e5e618b3f06; 204361a77f4018627addd4a06877448f088ddfc0 up to, but not including, d376c131af7c7739a87ff037ed2fdb67c2542c8a; 204361a77f4018627addd4a06877448f088ddfc0 up to, but not including, d6a2d7b04b5a093021a7a0e2e69e9d5237dfa8cc; 13f35a2c0fd5c6a4fcd8903542b053bcc914fcf5; 5.8.6 up to, but not including, 5.9; 5.9d6bda9df0c0a3080804181464d5c0f4d78a4e769, 5a20ebf0c81b61f5ea3b1b529c100cad69b9f603, 252c5051dba9c709b6a72f2866f93e5e618b3f06, d376c131af7c7739a87ff037ed2fdb67c2542c8a, d6a2d7b04b5a093021a7a0e2e69e9d5237dfa8cc, 5.9
LinuxLinux Kernel5.8.6 up to, but not including, 5.9; 5.9.1 up to, but not including, 6.6.141; 6.7 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10; 5.9; 7.15.9, 6.6.141, 6.12.91, 6.18.33, 7.0.10

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: io-wq: check that the predecessor is hashed in io_wq_remove_pending() io_wq_remove_pending() needs to fix up wq->hash_tail[] if the cancelled work was the tail of its hash bucket. When doing this, it checks whether the preceding entry in acct->work_list has the same hash value, but never checks that the predecessor is hashed at all. io_get_work_hash() is simply atomic_read(&work->flags) >> IO_WQ_HASH_SHIFT, and the hash bits are never set for non-hashed work, so it returns 0. Thus, when a hashed bucket-0 work is cancelled while a non-hashed work is its list predecessor, the check spuriously passes and a pointer to the non-hashed io_kiocb is stored in wq->hash_tail[0]. Because non-hashed work is dequeued via the fast path in io_get_next_work(), which never touches hash_tail[], the stale pointer is never cleared. Therefore, after the non-hashed io_kiocb completes and is freed back to req_cachep, wq->hash_tail[0] is a dangling pointer. The io_wq is per-task (tctx->io_wq) and survives ring open/close, so the dangling pointer persists for the lifetime of the task; the next hashed bucket-0 enqueue dereferences it in io_wq_insert_work() and wq_list_add_after() writes through freed memory. Add the missing io_wq_is_hashed() check so a non-hashed predecessor never inherits a hash_tail[] slot.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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