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net_sched: hfsc: Fix a UAF vulnerability in class handling (Linux Linux)

CVE-2025-37797
HIGH 7.8

At a glance

Source
NVD
EPSS
EPSS 0.22 % · percentile 13 ()
State
PUBLISHED
Published
Updated
Assigner
Linux
NVD status
Modified

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Description

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.

Weaknesses (CWE)

References

Scores

VersionScoreVectorScored by
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HLinux
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HNVD · 416baaa9-dc9f-4396-8d5f-8c081fb06d67 (Secondary)
CVSS 3.1HIGH 7.8CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HNVD · nvd@nist.gov (Primary)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
Linux · Linuxaffected 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 < 28b09a067831f7317c3841812276022d6c940677 ; affected 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 < 39b9095dd3b55d9b2743df038c32138efa34a9de ; affected 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 < fcc8ede663569c704fb00a702973bd6c00373283 ; affected 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 < 20d584a33e480ae80d105f43e0e7b56784da41b9 ; affected 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 < 3aa852e3605000d5c47035c3fc3a986d14ccfa9f ; affected 21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 < 86cd4641c713455a4f1c8e54c370c598c2b1cee0
Linux · Linuxaffected 4.14 ; unaffected 0 < 4.14 ; unaffected 5.4.293 ≤ 5.4.* ; unaffected 5.10.237 ≤ 5.10.* ; unaffected 5.15.181 ≤ 5.15.* ; unaffected 6.1.136 ≤ 6.1.*

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD