CVE-2025-37797

High

In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class handling This patch fixes a Use-After-Free vulnerability in the HFSC qdisc class handling. The issue occurs due to a time-of-check/time-of-use condition in hfsc_change_class() when working with certain child qdiscs like netem or codel. The vulnerability works as follows: 1. hfsc_change_class() checks if a class has packets (q.qlen != 0) 2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g., codel, netem) might drop packets and empty the queue 3. The code continues assuming the queue is still non-empty, adding the class to vttree 4. This breaks HFSC scheduler assumptions that only non-empty classes are in vttree 5. Later, when the class is destroyed, this can lead to a Use-After-Free The fix adds a second queue length check after qdisc_peek_len() to verify the queue wasn't emptied.

Package Linux Kernel
Published 2025-05-02
Last modified 2025-11-06
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.8

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness type

CWE-416

CVE-2025-37797 is a Use After Free vulnerability

What is Use After Free?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. Learn more on MITRE CWE

Affected versions

Linux kernel versions 4.14 and later are affected. Fixed in 5.4.293, 5.10.237, 5.15.181, 6.1.136, 6.6.89, 6.12.26, 6.14.5, 6.15 and their respective stable series.

Affected from
≥ 4.14
Fixed in
✓ 5.4.293 5.4.x ✓ 5.10.237 5.10.x ✓ 5.15.181 5.15.x ✓ 6.1.136 6.1.x ✓ 6.6.89 6.6.x ✓ 6.12.26 6.12.x ✓ 6.14.5 6.14.x ✓ 6.15

References

The following references provide additional information about CVE-2025-37797 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

8 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2025-37797?

    CVE-2025-37797 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 4.14 onward and has been patched in 5.4.293, 5.10.237, 5.15.181 and others. CVE-2025-37797 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2025-37797?

    CVE-2025-37797 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H .

  • Is there a patch available for CVE-2025-37797?

    Yes — CVE-2025-37797 has been patched. Fixed versions include 5.4.293, 5.10.237, 5.15.181 and others. If you are running Linux kernel 4.14 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2025-37797 actively exploited?

    No — CVE-2025-37797 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Use After Free (CWE-416)?

    The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. View CWE-416 on MITRE CWE →

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