Unknown

CVE-2026-74284 — net/sched: sch_hfsc: Don't make class passive twice

In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_hfsc: Don't make class passive twice update_vf() is called from two places for the same class during a single dequeue when the class's child qdisc (e.g. codel/fq_codel) drops its last packets while dequeuing: 1. The child calls qdisc_tree_reduce_backlog(), which, now that the child is empty, invokes hfsc_qlen_notify() -> update_vf(cl, 0, 0) and turns the class passive (cl_nactive is decremented up the hierarchy). 2. hfsc_dequeue() then calls update_vf(cl, qdisc_pkt_len(skb), cur_time) to charge the dequeued bytes. On the second call the class is already passive, but its child qdisc is still empty, so update_vf() arms go_passive again: if (cl->qdisc->q.qlen == 0 && cl->cl_flags & HFSC_FSC) go_passive = 1; The leaf is then skipped by the cl_nactive == 0 check inside the loop, which does not clear go_passive, so the stale go_passive propagates to the parent and decrements its cl_nactive a second time. A parent that still has other active children is driven to cl_nactive == 0 and removed from the vttree, even though those siblings are still backlogged. They are never dequeued again and the qdisc stalls. Fix this by only arming go_passive when the class is actually active, so an already-passive class no longer triggers a second passive transition. The byte accounting (cl->cl_total += len) still runs for every ancestor, so dequeued bytes continue to be counted exactly once.

Published Aug 15, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+2

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.22%

ahead of 12% of scored CVEs · Oct 29, 2026

Affects

Linux

CVSS base

—

Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	version c1175c4ad01dbc9c979d099861fa90a754f72059version 6.15≥ 6.14.6 and < 6.15≥ 5.4.297 and < 5.5≥ 6.12.28 and < 6.12.97≥ 6.6.90 and < 6.6.145≥ 6.1.138 and < 6.1.178≥ 5.15.190 and < 5.15.212 and 10 more ≥ 5.10.241 and < 5.10.261≥ 72c61ffbeeb8c50f6d4d70c65d3283aa1bac57a7 and < a425c82ff06cda5165e0de3de8c2a445ec1f863eversion 9a5fd5c2f4d4afdd5e405083ee53e0789ce76956≥ 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb and < 90b662ea25f5e83bb3b8ccec5b93ced810b92fb8≥ 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb and < 3a49bbae676fef1ffe548971e6229ae2adeb9d10≥ 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb and < 66dbb13eeb2fc339f8f548a9076be4c1a94857b0≥ d06476714d2819b550e0cc39222347e2c8941c9d and < 9221a594c72a1446137926d4c2aa04e345f798dc≥ 9030a91235ae4845ec71902c3e0cecfc9ed1f2df and < b2a017bfcf565721918ec7355a373911d2f2a227≥ 0475c85426b18eccdcb7f9fb58d8f8e9c6c58c87 and < 15720cd8fa3fc625146128f89a8e11b0449a20a7≥ a5efc95a33bd4fcb879250852828cc58c7862970 and < fc973ecd1a079b9a87c360478542f3a56dea085b	Vulnerable	CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 29, 2026 · 14 reading(s) · max 0.22%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Aug 15, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

git.kernel.org/stable/c/b2a017bfcf565721918ec7355a373911d2f2a227
NIST National Vulnerability Database
git.kernel.org/stable/c/9221a594c72a1446137926d4c2aa04e345f798dc
NIST National Vulnerability Database
git.kernel.org/stable/c/fc973ecd1a079b9a87c360478542f3a56dea085b
NIST National Vulnerability Database
git.kernel.org/stable/c/a425c82ff06cda5165e0de3de8c2a445ec1f863e
NIST National Vulnerability Database
git.kernel.org/stable/c/3a49bbae676fef1ffe548971e6229ae2adeb9d10
NIST National Vulnerability Database
git.kernel.org/stable/c/15720cd8fa3fc625146128f89a8e11b0449a20a7
NIST National Vulnerability Database
git.kernel.org/stable/c/90b662ea25f5e83bb3b8ccec5b93ced810b92fb8
NIST National Vulnerability Database
git.kernel.org/stable/c/66dbb13eeb2fc339f8f548a9076be4c1a94857b0
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Unknown CVE-2026-99216 Drivers: hv: Don't reset VMBus connection state on error/exit paths 2d
Unknown CVE-2026-99215 power: supply: core: prevent unregistering a power supply while a callback runs 2d
Unknown CVE-2026-99207 scsi: target: Disable interrupts while holding delayed_cmd_lock 2d
Unknown CVE-2026-99208 drm/xe/oa: Zero OA buffer at allocation 2d
Unknown CVE-2026-99209 drm/xe: skip eviction of a BO with no resource 2d
Unknown CVE-2026-99210 accel/rocket: clear rdev on device init failure 2d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CVSS score published by NVD, the CNA, CISA or GitHub so far.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-74284 is "net/sched: sch_hfsc: Don't make class passive twice", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.22% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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