CyberSecBulletin
CVE-2026-64017NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-64017 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 a3fefe65b94b095c9b66420ee0ecabd9fc2e1568, f122d9968d730c2e71d5e59d0d8b7d67acb5b3bb, 23d8ea1e303b5f32d883757a4a707e791dbc9808 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 0.13% 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 a3fefe65b94b095c9b66420ee0ecabd9fc2e1568 or f122d9968d730c2e71d5e59d0d8b7d67acb5b3bb or 23d8ea1e303b5f32d883757a4a707e791dbc9808 or 97e2d08de282ef76f84ab4ccd00f1acb3f5f999e, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.2 or 6.6 or 6.7 or 6.12.104, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxb5c8e0ff76d10f6bf70a7237678f27c20cf59bc9 up to, but not including, a3fefe65b94b095c9b66420ee0ecabd9fc2e1568; b80056bd75a16e4550873ecefe12bc8fd190b1cf up to, but not including, f122d9968d730c2e71d5e59d0d8b7d67acb5b3bb; b0077e269f6c152e807fdac90b58caf012cdbaab up to, but not including, 23d8ea1e303b5f32d883757a4a707e791dbc9808; b0077e269f6c152e807fdac90b58caf012cdbaab up to, but not including, 97e2d08de282ef76f84ab4ccd00f1acb3f5f999e; b0077e269f6c152e807fdac90b58caf012cdbaab up to, but not including, 388468f7e7d1eab092cf2a39fdfb502e52019ec6; b0077e269f6c152e807fdac90b58caf012cdbaab up to, but not including, dc278e9bf2b9513a763353e6b9cc21e0f532954e; e9c309ded295b7f8849097d71ae231456ca79f78; 33cf52b6e53a6aa55883aa7fb9ceffceff8488a6; and 5 more rangesa3fefe65b94b095c9b66420ee0ecabd9fc2e1568, f122d9968d730c2e71d5e59d0d8b7d67acb5b3bb, 23d8ea1e303b5f32d883757a4a707e791dbc9808, 97e2d08de282ef76f84ab4ccd00f1acb3f5f999e, 388468f7e7d1eab092cf2a39fdfb502e52019ec6, dc278e9bf2b9513a763353e6b9cc21e0f532954e
LinuxLinux Kernel6.1.72 up to, but not including, 6.2; 6.1.75 up to, but not including, 6.2; 6.5.13 up to, but not including, 6.6; 6.6.3 up to, but not including, 6.7; 6.6.14 up to, but not including, 6.7; 6.7.1 up to, but not including, 6.12.104; 6.13 up to, but not including, 6.18.45; 6.19 up to, but not including, 7.0.11; and 2 more ranges6.2, 6.6, 6.7, 6.12.104, 6.18.45, 7.0.11

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: blk-mq: pop cached request if it is usable When submitting a bio to blk-mq, if the task should sleep after peeking a cached request, but before it pops it, the plug flushes and calls blk_mq_free_plug_rqs, freeing the cached_rqs. This creates a use-after-free bug. Fix this by popping the cached request before any possible blocking calls if it is suitable for use. Popping this request first holds a queue reference, so avoid any serialization races with queue freezes and can safely proceed with dispatching that request to the driver. This potentially increases a timing window from when a driver wants to freeze its queue to when requests stop being dispatched. That scenario is off the fast path though, and drivers need to appropriately handle requests during a freeze request anyway. The downside is the popped element needs to be individually freed when we performed a bio plug merge. The cached request would have had to be freed later anyway, but this patch does it inline with building the plug list instead of after flushing it.

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. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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