CVE-2025-38477 | net/sched: sch_qfq: Fix race condition on qfq_aggregate

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_qfq: Fix race condition on qfq_aggregate A race condition can occur when 'agg' is modified in qfq_change_agg (called during qfq_enqueue) while other threads access it concurrently. For example, qfq_dump_class may trigger a NULL dereference, and qfq_delete_class may cause a use-after-free. This patch addresses the issue by: 1. Moved qfq_destroy_class into the critical section. 2. Added sch_tree_lock protection to qfq_dump_class and qfq_dump_class_stats.

Published: 2025-07-28 Last update: 2026-05-12 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Conclusion & alert: CVE-2025-38477 is rated Low Risk (19.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.01%). Mandatory action: Low composite risk—no urgent action required; patch on your normal maintenance cycle and revisit priority if CVSS or EPSS increases.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-38477

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-24 0.06% 0.01% -0.05%
2 2025-11-27 0.02% 0.06% +0.05%
3 2025-07-28 0.02%

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-38477

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.7 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
1.0 3.6 [email protected]

Weakness enumeration for CVE-2025-38477

GitHub Security Advisory for CVE-2025-38477

GHSA-79vc-v8qm-8x53 · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_qfq: Fix race...

OS Trackers for CVE-2025-38477

vendor priority summary link
debian not yet assigned CVE-2025-38477 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2025-38477
redhat medium https://access.redhat.com/security/cve/CVE-2025-38477
suse high https://www.suse.com/security/cve/CVE-2025-38477/
ubuntu medium CVE-2025-38477 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, released 209, ignored 158, not-affected 23, needed 5, needs-triage 2. https://ubuntu.com/security/CVE-2025-38477

Affected software / configurations for CVE-2025-38477

Vendor Product Version Raw CPE
linux linux_kernel >= 3.8, < 5.4.297 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.5, < 5.10.241 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.190 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.147 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.100 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.40 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.15.8 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 6.16 cpe:2.3:o:linux:linux_kernel:6.16:rc1:*:*:*:*:*:*
linux linux_kernel 6.16 cpe:2.3:o:linux:linux_kernel:6.16:rc2:*:*:*:*:*:*
linux linux_kernel 6.16 cpe:2.3:o:linux:linux_kernel:6.16:rc3:*:*:*:*:*:*
linux linux_kernel 6.16 cpe:2.3:o:linux:linux_kernel:6.16:rc4:*:*:*:*:*:*
linux linux_kernel 6.16 cpe:2.3:o:linux:linux_kernel:6.16:rc5:*:*:*:*:*:*
linux linux_kernel 6.16 cpe:2.3:o:linux:linux_kernel:6.16:rc6:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-38477

URL Tags
https://git.kernel.org/stable/c/466e10194ab81caa2ee6a332d33ba16bcceeeba6 Patch
https://git.kernel.org/stable/c/5e28d5a3f774f118896aec17a3a20a9c5c9dfc64 Patch
https://git.kernel.org/stable/c/a6d735100f602c830c16d69fb6d780eebd8c9ae1 Patch
https://git.kernel.org/stable/c/aa7a22c4d678bf649fd3a1d27debec583563414d Patch
https://git.kernel.org/stable/c/c000a3a330d97f6c073ace5aa5faf94b9adb4b79 Patch
https://git.kernel.org/stable/c/c6df794000147a3a02f79984aada4ce83f8d0a1e Patch
https://git.kernel.org/stable/c/d841aa5518508ab195b6781ad0d73ee378d713dd Patch
https://git.kernel.org/stable/c/fbe48f06e64134dfeafa89ad23387f66ebca3527 Patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Mailing List Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
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