CVE-2025-37797

HIGH EPSS 6.3%
Published May 2, 20251y ago · Modified Jun 17, 20261w ago
7.8 CVSS 3.1
High
Find Similar
Published May 2, 2025 1y ago
Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score
7.8
Exploitability
1.8
Impact
5.9
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
6.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-416 Use After Free Memory Safety

Affected Products 19

VendorProductVersionRange
linuxlinux_kernel*≥4.14.1  –  <5.4.293
linuxlinux_kernel*≥5.5  –  <5.10.237
linuxlinux_kernel*≥5.11  –  <5.15.181
linuxlinux_kernel*≥5.16  –  <6.1.136
linuxlinux_kernel*≥6.2  –  <6.6.89
linuxlinux_kernel*≥6.7  –  <6.12.26
linuxlinux_kernel*≥6.13  –  <6.14.5
linuxlinux_kernel4.14any
linuxlinux_kernel4.14any
linuxlinux_kernel4.14any
linuxlinux_kernel4.14any
linuxlinux_kernel4.14any
linuxlinux_kernel4.14any
linuxlinux_kernel4.14any
linuxlinux_kernel4.14any
linuxlinux_kernel6.15any
linuxlinux_kernel6.15any
linuxlinux_kernel6.15any
debiandebian_linux11.0any

References 10

  • git.kernel.org https://git.kernel.org/stable/c/20d584a33e480ae80d105f43e0e7b56784da41b9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/28b09a067831f7317c3841812276022d6c940677
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/39b9095dd3b55d9b2743df038c32138efa34a9de
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3aa852e3605000d5c47035c3fc3a986d14ccfa9f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3df275ef0a6ae181e8428a6589ef5d5231e58b5c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/86cd4641c713455a4f1c8e54c370c598c2b1cee0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/bb583c88d23b72d8d16453d24856c99bd93dadf5
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/fcc8ede663569c704fb00a702973bd6c00373283
    Patch
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
    Mailing ListThird Party Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html
    Mailing ListThird Party Advisory

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/20d584a33e480ae80d105f43e0e7b56784da41b9
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/28b09a067831f7317c3841812276022d6c940677
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/39b9095dd3b55d9b2743df038c32138efa34a9de
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3aa852e3605000d5c47035c3fc3a986d14ccfa9f
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3df275ef0a6ae181e8428a6589ef5d5231e58b5c
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/86cd4641c713455a4f1c8e54c370c598c2b1cee0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/bb583c88d23b72d8d16453d24856c99bd93dadf5
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/fcc8ede663569c704fb00a702973bd6c00373283
    Patch