CVE-2025-37797

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Source
https://cve.org/CVERecord?id=CVE-2025-37797
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-37797.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2025-37797
Downstream
Related
Published
2025-05-02T14:16:01.905Z
Modified
2026-05-15T11:53:37.719515125Z
Summary
net_sched: hfsc: Fix a UAF vulnerability in class handling
Details

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 hfscchangeclass() when working with certain child qdiscs like netem or codel.

The vulnerability works as follows: 1. hfscchangeclass() checks if a class has packets (q.qlen != 0) 2. It then calls qdiscpeeklen(), 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 qdiscpeeklen() to verify the queue wasn't emptied.

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37797.json"
}
References

Affected packages

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
4.14.0
Fixed
5.4.293
Type
ECOSYSTEM
Events
Introduced
5.5.0
Fixed
5.10.237
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.181
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.136
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.89
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.26
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.14.5

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-37797.json"