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Vulnerabilities

Vulnerability · CVE-2025-38177

In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its

Published Jul 4, 2025 · catalog updated Aug 5, 2026 · Linux Linux

Check if you run it

No confirmed exploitation is on record for CVE-2025-38177. EPSS is 0.20%. 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
0.20%
Remediation
Vendor / distro source
Affected products
vendor Linux Linux patch: 5.4.297

In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life: 1. update_vf() decreases cl->cl_nactive, so we can check whether it is non-zero before calling it. 2. eltree_remove() always removes RB node cl->el_node, but we can use RB_EMPTY_NODE() + RB_CLEAR_NODE() to make it safe.

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 patch: 5.4.297patch: 5.4.297

How to fix CVE-2025-38177

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-2025-38177. EPSS is 0.20%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with Linux Linux patch: 5.4.297 patch: 5.4.297. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.20%. 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. Jul 4, 2025 · EUVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life: 1. update_vf() decreases cl->cl_nactive, so we can check whether it is non-zero before calling it. 2. eltree_

  2. Aug 5, 2026 · EUVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life: 1. update_vf() decreases cl->cl_nactive, so we can check whether it is non-zero before calling it. 2. eltree_

Sources

  • CVE.orgVulnerability recordCVE-2025-38177

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-38177

    30-day exploitation probability 0.20%

    first.org
  • EUVDVulnerability recordEUVD-2025-20019

    In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() call

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 21, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.