CVE-2025-37797 (GCVE-0-2025-37797)
Vulnerability from cvelistv5 – Published: 2025-05-02 14:16 – Updated: 2026-08-05 11:57
VLAI
EPSS
VEX
Title
net_sched: hfsc: Fix a UAF vulnerability in class handling
Summary
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.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-10 20:40 UTC
Assigner
References
10 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < 28b09a067831f7317c3841812276022d6c940677
(git)
Affected: 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < 39b9095dd3b55d9b2743df038c32138efa34a9de (git) Affected: 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < fcc8ede663569c704fb00a702973bd6c00373283 (git) Affected: 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < 20d584a33e480ae80d105f43e0e7b56784da41b9 (git) Affected: 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < 3aa852e3605000d5c47035c3fc3a986d14ccfa9f (git) Affected: 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < 86cd4641c713455a4f1c8e54c370c598c2b1cee0 (git) Affected: 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < bb583c88d23b72d8d16453d24856c99bd93dadf5 (git) Affected: 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 , < 3df275ef0a6ae181e8428a6589ef5d5231e58b5c (git) |
guessed | |
| Linux | Linux |
Affected:
4.14
Unaffected: 0 , < 4.14 (semver) Unaffected: 5.4.293 , ≤ 5.4.* (semver) Unaffected: 5.10.237 , ≤ 5.10.* (semver) Unaffected: 5.15.181 , ≤ 5.15.* (semver) Unaffected: 6.1.136 , ≤ 6.1.* (semver) Unaffected: 6.6.89 , ≤ 6.6.* (semver) Unaffected: 6.12.26 , ≤ 6.12.* (semver) Unaffected: 6.14.5 , ≤ 6.14.* (semver) Unaffected: 6.15 , ≤ * (original_commit_for_fix) |
guessed |
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Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline
Sightings and recorded dates, grouped by day · UTC
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.