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Vulnerabilities

Vulnerability · CVE-2025-37953

In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after w

Published May 20, 2025 · catalog updated May 11, 2026 · Linux Linux

Check if you run it

No confirmed exploitation is on record for CVE-2025-37953. EPSS is 0.19%. 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
None0.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.19%
Remediation
Version ranges on file
Affected products
vendor Linux Linux a61f1b5921761fbaf166231418bc1db301e5bf59 <c4792b9e38d2f61b07eac72f10909fa76130314b

In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent. It turns out in the following case it introduced some regression: htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate() |-> htb_next_rb_node() |-> htb_deactivate() For htb_next_rb_node(), after calling the 1st htb_deactivate(), the clprio[prio]->ptr could be already set to NULL, which means htb_next_rb_node() is vulne

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 a61f1b5921761fbaf166231418bc1db301e5bf59 <c4792b9e38d2f61b07eac72f10909fa76130314ba61f1b5921761fbaf166231418bc1db301e5bf59 <c4792b9e38d2f61b07eac72f10909fa76130314b

How to fix CVE-2025-37953

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-2025-37953. EPSS is 0.19%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Compare what you have installed with Linux Linux a61f1b5921761fbaf166231418bc1db301e5bf59 <c4792b9e38d2f61b07eac72f10909fa76130314b a61f1b5921761fbaf166231418bc1db301e5bf59 <c4792b9e38d2f61b07eac72f10909fa76130314b. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.19%. 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 20, 2025 · EUVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent. It turns out in the following case it introduced some regression: htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate()

  2. May 11, 2026 · EUVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent. It turns out in the following case it introduced some regression: htb_dequeue_tree(): |-> fq_codel_dequeue() |-> qdisc_tree_reduce_backlog() |-> htb_qlen_notify() |-> htb_deactivate()

Sources

  • CVE.orgVulnerability recordCVE-2025-37953

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-37953

    30-day exploitation probability 0.2%

    first.org
  • EUVDVulnerability recordEUVD-2025-15902

    In the Linux kernel, the following vulnerability has been resolved: sch_htb: make htb_deactivate() idempotent Alan reported a NULL pointer dereference in htb_next_rb_node() after we made htb_qlen_notify() idempotent. It turns out in the following case it introduced some regressio

    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.