CVE-2025-38177 | sch_hfsc: make hfsc_qlen_notify() idempotent

In the Linux kernel, the following vulnerability has been resolved: sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life: 1. update_vf() decreases cl->cl_nactive, so we can check whether it is non-zero before calling it. 2. eltree_remove() always removes RB node cl->el_node, but we can use RB_EMPTY_NODE() + RB_CLEAR_NODE() to make it safe.

Published: 2025-07-04 Last update: 2025-12-18 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-38177 is rated Low Risk (31/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.09%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

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-2025-38177

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 2026-04-30 0.03% 0.09% +0.06%
2 2025-12-19 0.05% 0.03% -0.02%
3 2025-08-29 — 0.05% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-38177

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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.
 1.8 3.6 [email protected]

Weakness enumeration for CVE-2025-38177

OS Trackers for CVE-2025-38177

vendor priority summary link
debian not yet assigned CVE-2025-38177 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-2025-38177
redhat medium — https://access.redhat.com/security/cve/CVE-2025-38177
suse high — https://www.suse.com/security/cve/CVE-2025-38177/
ubuntu medium CVE-2025-38177 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 222, ignored 152, not-affected 28, needs-triage 3, needed 1. https://ubuntu.com/security/CVE-2025-38177

Affected software / configurations for CVE-2025-38177

Vendor Product Version Raw CPE
linux linux_kernel < 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, < 6.1.138 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.90 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.28 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.14.6 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 6.15 cpe:2.3:o:linux:linux_kernel:6.15:rc1:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-38177

URL Tags
https://git.kernel.org/stable/c/0475c85426b18eccdcb7f9fb58d8f8e9c6c58c87 Patch
https://git.kernel.org/stable/c/51eb3b65544c9efd6a1026889ee5fb5aa62da3bb Patch
https://git.kernel.org/stable/c/72c61ffbeeb8c50f6d4d70c65d3283aa1bac57a7 Patch
https://git.kernel.org/stable/c/9030a91235ae4845ec71902c3e0cecfc9ed1f2df Patch
https://git.kernel.org/stable/c/9a5fd5c2f4d4afdd5e405083ee53e0789ce76956 Patch
https://git.kernel.org/stable/c/a5efc95a33bd4fcb879250852828cc58c7862970 Patch
https://git.kernel.org/stable/c/c1175c4ad01dbc9c979d099861fa90a754f72059 Patch
https://git.kernel.org/stable/c/d06476714d2819b550e0cc39222347e2c8941c9d Patch
https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Third Party Advisory
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