CyberSecBulletin
CVE-2026-53273NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-53273 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 416259cb5bffecaaae5f76539deb535a8c1b2c34, 724d0caffd4204b46f78efe22f18f8338031c6e1, ae847ab29ded2d7cece4d5970f0edefa4137bf2f 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 0.15% 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 416259cb5bffecaaae5f76539deb535a8c1b2c34 or 724d0caffd4204b46f78efe22f18f8338031c6e1 or ae847ab29ded2d7cece4d5970f0edefa4137bf2f or 9a0dc9279d0907b198f205a693aedf696b08145d, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.5 or 5.10.259 or 5.15.210 or 6.1.176, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux0180cf0373f84fff61b16f8c062553a13dd7cfca up to, but not including, 416259cb5bffecaaae5f76539deb535a8c1b2c34; c0a9a948159153be145f9471435695373904ee6d up to, but not including, 724d0caffd4204b46f78efe22f18f8338031c6e1; ec18520f5edc20a00c34a8c9fdd6507c355e880f up to, but not including, ae847ab29ded2d7cece4d5970f0edefa4137bf2f; d61cc1a435e6894bfb0dd3370c6f765d2d12825d up to, but not including, 9a0dc9279d0907b198f205a693aedf696b08145d; fd9d2d6124c293e40797a080adf8a9c237efd8b8 up to, but not including, d366a01475f927402c96a3fe78bfc06b924fc87d; 70b0d6b0a199c5a3ee6c72f5e61681ed6f759612 up to, but not including, d5b57bb314d79e99bebb58a53588fa11dd4dbf69; 70b0d6b0a199c5a3ee6c72f5e61681ed6f759612 up to, but not including, 373152c94e57e9592b68c100e224fbd943cfd608; 70b0d6b0a199c5a3ee6c72f5e61681ed6f759612 up to, but not including, 387a926ee166814611acecb960207fe2f3c4fd3e; and 10 more ranges416259cb5bffecaaae5f76539deb535a8c1b2c34, 724d0caffd4204b46f78efe22f18f8338031c6e1, ae847ab29ded2d7cece4d5970f0edefa4137bf2f, 9a0dc9279d0907b198f205a693aedf696b08145d, d366a01475f927402c96a3fe78bfc06b924fc87d, d5b57bb314d79e99bebb58a53588fa11dd4dbf69
LinuxLinux Kernel5.4.291 up to, but not including, 5.5; 5.10.235 up to, but not including, 5.10.259; 5.15.179 up to, but not including, 5.15.210; 6.1.130 up to, but not including, 6.1.176; 6.6.80 up to, but not including, 6.6.143; 6.12.17 up to, but not including, 6.12.94; 6.13.5 up to, but not including, 6.14; 6.14.1 up to, but not including, 6.18.36; and 3 more ranges5.5, 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94

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: tee: optee: prevent use-after-free when the client exits before the supplicant Commit 70b0d6b0a199 ("tee: optee: Fix supplicant wait loop") made the client wait as killable so it can be interrupted during shutdown or after a supplicant crash. This changes the original lifetime expectations: the client task can now terminate while the supplicant is still processing its request. If the client exits first it removes the request from its queue and kfree()s it, while the request ID remains in supp->idr. A subsequent lookup on the supplicant path then dereferences freed memory, leading to a use-after-free. Serialise access to the request with supp->mutex: * Hold supp->mutex in optee_supp_recv() and optee_supp_send() while looking up and touching the request. * Let optee_supp_thrd_req() notice that the client has terminated and signal optee_supp_send() accordingly. With these changes the request cannot be freed while the supplicant still has a reference, eliminating the race.

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

Spotted an error? Tell us.