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
2025-05-02T14:16:01Z
Modified
2026-08-12T03:30:36Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
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 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.

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

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14
Fixed
28b09a067831f7317c3841812276022d6c940677
Fixed
39b9095dd3b55d9b2743df038c32138efa34a9de
Fixed
fcc8ede663569c704fb00a702973bd6c00373283
Fixed
20d584a33e480ae80d105f43e0e7b56784da41b9
Fixed
3aa852e3605000d5c47035c3fc3a986d14ccfa9f
Fixed
86cd4641c713455a4f1c8e54c370c598c2b1cee0
Fixed
bb583c88d23b72d8d16453d24856c99bd93dadf5
Fixed
3df275ef0a6ae181e8428a6589ef5d5231e58b5c

Database specific

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

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"