CVE-2025-38177: sch_hfsc: make hfsc_qlen_notify() idempotent
Vulnerability summary
CVE-2025-38177 is a high (CVSS 7.8) Incomplete Cleanup vulnerability in debian debian_linux. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 11.4% of scored vulnerabilities.
Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 99 · Related 86Timeline
- 04-07-2025PublishedVulnerability first disclosed.
- 05-08-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated7.8HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
- NVDNIST5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HDiffers
EPSS trend
Probability
0.21%
Chance of exploitation in the next 30 days
Percentile
11%
Versus all other CVEs
30-day change
Increase +0.02 pp
From 0.19% on 04-10-2026
Known exploited
Compare KEV catalogsNot in the CISA KEV catalog.
Not in the ENISA CNW catalog.
Not in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu141 products
- linux< 4.15.0-239.251 | < 5.4.0-219.239 | < 5.15.0-143.153 | < 6.8.0-63.66
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws< 4.15.0-1182.195 | < 5.4.0-1148.158 | < 5.15.0-1087.94 | < 6.8.0-1031.33
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.1.139-1 | < 6.12.29-1
- debian_linuxEOL11.0
Linux2 products
- linux≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < 9a5fd5c2f4d4afdd5e405083ee53e0789ce76956 | ≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < 72c61ffbeeb8c50f6d4d70c65d3283aa1bac57a7 | ≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < a5efc95a33bd4fcb879250852828cc58c7862970 | ≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < 0475c85426b18eccdcb7f9fb58d8f8e9c6c58c87 | ≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < 9030a91235ae4845ec71902c3e0cecfc9ed1f2df | ≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < d06476714d2819b550e0cc39222347e2c8941c9d | ≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < c1175c4ad01dbc9c979d099861fa90a754f72059 | ≥ 959466588aa7f84ccf79ae36a1d89542eaf9aaec, < 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb | 4.14
- linux_kernel< 5.4.297 | ≥ 5.5, < 5.10.241 | ≥ 5.11, < 5.15.190 | ≥ 5.16, < 6.1.138 | ≥ 6.2, < 6.6.90 | ≥ 6.7, < 6.12.28 | ≥ 6.13, < 6.14.6 | 6.15:rc1
3 vendors · 145 products
References
24 links- lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlThird Party Advisory
- lists.debian.org/debian-lts-announce/2025/08/msg00010.htmlThird Party Advisory