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Vulnerabilities

Vulnerability · CVE-2025-37797

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 th

Published May 2, 2025 · catalog updated Aug 5, 2026 · Linux Linux

Check if you run it

No confirmed exploitation is on record for CVE-2025-37797. EPSS is 0.22%. Act only if a listed version of Linux Linux is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.22%
Remediation
Version ranges on file
Affected products
vendor Linux Linux 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <20d584a33e480ae80d105f43e0e7b56784da41b9

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 a

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Linux Linux 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <20d584a33e480ae80d105f43e0e7b56784da41b921f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <20d584a33e480ae80d105f43e0e7b56784da41b9

How to fix CVE-2025-37797

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-37797. EPSS is 0.22%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with Linux Linux 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <20d584a33e480ae80d105f43e0e7b56784da41b9 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <20d584a33e480ae80d105f43e0e7b56784da41b9. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.22%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 2, 2025 · EUVD

    Detected

    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_ch

  2. Aug 5, 2026 · EUVD

    Updated

    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_ch

Sources

  • CVE.orgVulnerability recordCVE-2025-37797

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-37797

    30-day exploitation probability 0.2%

    first.org
  • EUVDVulnerability recordEUVD-2025-13245

    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_c

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.