CyberSecBulletin
CVE-2025-37838NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2025-37838 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 d03abc1c2b21324550fa71e12d53e7d3498e0af6, 4a8c29beb8a02b5a0a9d77d608aa14b6f88a6b86, 72972552d0d0bfeb2dec5daf343a19018db36ffa 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 0.25% 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 d03abc1c2b21324550fa71e12d53e7d3498e0af6 or 4a8c29beb8a02b5a0a9d77d608aa14b6f88a6b86 or 72972552d0d0bfeb2dec5daf343a19018db36ffa or d58493832e284f066e559b8da5ab20c15a2801d3, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.135 or 6.6.88 or 6.12.24 or 6.13.12, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxdf26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, d03abc1c2b21324550fa71e12d53e7d3498e0af6; df26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, 4a8c29beb8a02b5a0a9d77d608aa14b6f88a6b86; df26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, 72972552d0d0bfeb2dec5daf343a19018db36ffa; df26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, d58493832e284f066e559b8da5ab20c15a2801d3; df26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, 58eb29dba712ab0f13af59ca2fe545f5ce360e78; df26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, ae5a6a0b425e8f76a9f0677e50796e494e89b088; df26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, 834e602d0cc7c743bfce734fad4a46cefc0f9ab1; df26d639e2f4628732a8da5a0f71e4e652ce809b up to, but not including, 4b4194c9a7a8f92db39e8e86c85f4fb12ebbec4f; and 2 more rangesd03abc1c2b21324550fa71e12d53e7d3498e0af6, 4a8c29beb8a02b5a0a9d77d608aa14b6f88a6b86, 72972552d0d0bfeb2dec5daf343a19018db36ffa, d58493832e284f066e559b8da5ab20c15a2801d3, 58eb29dba712ab0f13af59ca2fe545f5ce360e78, ae5a6a0b425e8f76a9f0677e50796e494e89b088
LinuxLinux Kernelbefore 6.1.135; 6.2 up to, but not including, 6.6.88; 6.7 up to, but not including, 6.12.24; 6.13 up to, but not including, 6.13.12; 6.14 up to, but not including, 6.14.36.1.135, 6.6.88, 6.12.24, 6.13.12, 6.14.3

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 CISA (ADP).

Official description

In the Linux kernel, the following vulnerability has been resolved: HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition In the ssi_protocol_probe() function, &ssi->work is bound with ssip_xmit_work(), In ssip_pn_setup(), the ssip_pn_xmit() function within the ssip_pn_ops structure is capable of starting the work. If we remove the module which will call ssi_protocol_remove() to make a cleanup, it will free ssi through kfree(ssi), while the work mentioned above will be used. The sequence of operations that may lead to a UAF bug is as follows: CPU0 CPU1 | ssip_xmit_work ssi_protocol_remove | kfree(ssi); | | struct hsi_client *cl = ssi->cl; | // use ssi Fix it by ensuring that the work is canceled before proceeding with the cleanup in ssi_protocol_remove().

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.