CyberSecBulletin
CVE-2026-53046NVD status: Analyzed

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-53046 is a critical-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 57b47231055b431ed0a1a55f33cac32981564405, cc2da381875d4a67026e4c8feb3dba51a2a2d1bc, 8fcefe840fa8c14ce667768e5b043286ac3bbcbe 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 0.72% chance of exploitation within 30 days, higher than 54% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to 57b47231055b431ed0a1a55f33cac32981564405 or cc2da381875d4a67026e4c8feb3dba51a2a2d1bc or 8fcefe840fa8c14ce667768e5b043286ac3bbcbe or 8ef183216feaa24b66b940510d8b68f680eb56e9, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.209 or 6.1.175 or 6.6.141 or 6.12.91, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxe2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 57b47231055b431ed0a1a55f33cac32981564405; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, cc2da381875d4a67026e4c8feb3dba51a2a2d1bc; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 8fcefe840fa8c14ce667768e5b043286ac3bbcbe; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 8ef183216feaa24b66b940510d8b68f680eb56e9; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 7164b3953cefd540e7ebca828c793bc6869cfbc4; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, b46aa129fa2807bfe1545fe74d9295d53c51520b; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 up to, but not including, 3e298897f41c61450c2e7a4f457e8b2485eb35b3; 5.1557b47231055b431ed0a1a55f33cac32981564405, cc2da381875d4a67026e4c8feb3dba51a2a2d1bc, 8fcefe840fa8c14ce667768e5b043286ac3bbcbe, 8ef183216feaa24b66b940510d8b68f680eb56e9, 7164b3953cefd540e7ebca828c793bc6869cfbc4, b46aa129fa2807bfe1545fe74d9295d53c51520b
LinuxLinux Kernel5.15 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 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, 7.0.105.15.209, 6.1.175, 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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
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:N/AC:L/PR:N/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: ksmbd: fix use-after-free from async crypto on Qualcomm crypto engine ksmbd_crypt_message() sets a NULL completion callback on AEAD requests and does not handle the -EINPROGRESS return code from async hardware crypto engines like the Qualcomm Crypto Engine (QCE). When QCE returns -EINPROGRESS, ksmbd treats it as an error and immediately frees the request while the hardware DMA operation is still in flight. The DMA completion callback then dereferences freed memory, causing a NULL pointer crash: pc : qce_skcipher_done+0x24/0x174 lr : vchan_complete+0x230/0x27c ... el1h_64_irq+0x68/0x6c ksmbd_free_work_struct+0x20/0x118 [ksmbd] ksmbd_exit_file_cache+0x694/0xa4c [ksmbd] Use the standard crypto_wait_req() pattern with crypto_req_done() as the completion callback, matching the approach used by the SMB client in fs/smb/client/smb2ops.c. This properly handles both synchronous engines (immediate return) and async engines (-EINPROGRESS followed by callback notification).

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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