Skip to content
Noroxi
NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 15720cd8fa3fc625146128f89a8e11b0449a20a7, 3a49bbae676fef1ffe548971e6229ae2adeb9d10, 5.10.261.

Low priority for now. Upgrade to Linux Linux 15720cd8fa3fc625146128f89a8e11b0449a20a7, 3a49bbae676fef1ffe548971e6229ae2adeb9d10, 5.10.261 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Aug 15, 2026
Updated
Nov 6, 2026
EPSS
0.2% · 12th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-74284

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for linux records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 9a5fd5c2f4d4afdd5e405083ee53e0789ce76956, c1175c4ad01dbc9c979d099861fa90a754f72059, 6.15affected
    • 72c61ffbeeb8c50f6d4d70c65d3283aa1bac57a7 and later · before a425c82ff06cda5165e0de3de8c2a445ec1f863eaffected · git
    • a5efc95a33bd4fcb879250852828cc58c7862970 and later · before fc973ecd1a079b9a87c360478542f3a56dea085baffected · git
    • 0475c85426b18eccdcb7f9fb58d8f8e9c6c58c87 and later · before 15720cd8fa3fc625146128f89a8e11b0449a20a7affected · git
    • 9030a91235ae4845ec71902c3e0cecfc9ed1f2df and later · before b2a017bfcf565721918ec7355a373911d2f2a227affected · git
    • d06476714d2819b550e0cc39222347e2c8941c9d and later · before 9221a594c72a1446137926d4c2aa04e345f798dcaffected · git
    • 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb and later · before 66dbb13eeb2fc339f8f548a9076be4c1a94857b0affected · git
    • 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb and later · before 3a49bbae676fef1ffe548971e6229ae2adeb9d10affected · git
    • 51eb3b65544c9efd6a1026889ee5fb5aa62da3bb and later · before 90b662ea25f5e83bb3b8ccec5b93ced810b92fb8affected · git
    • 5.10.241 and later · before 5.10.261affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-74282Aug 15, 2026 · tipc: prevent snt_unacked underflow on CONN_ACK
    30Monitor
  • ← EarlierCVE-2026-74283Aug 15, 2026 · tipc: require net admin for TIPCv2 netlink mutators
    31Monitor
  • Later →CVE-2026-74287Aug 15, 2026 · sctp: validate embedded address parameter length
    36Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux15720cd8fa3fc625146128f89a8e11b0449a20a7Vendor (CNA)
Linux Linux3a49bbae676fef1ffe548971e6229ae2adeb9d10Vendor (CNA)
Linux Linux5.10.261Vendor (CNA)
Linux Linux5.15.212Vendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux6.1.178Vendor (CNA)
Linux Linux6.12.97Vendor (CNA)
Linux Linux6.15Vendor (CNA)
Linux Linux6.6.145Vendor (CNA)
Linux Linux66dbb13eeb2fc339f8f548a9076be4c1a94857b0Vendor (CNA)
Linux Linux90b662ea25f5e83bb3b8ccec5b93ced810b92fb8Vendor (CNA)
Linux Linux9221a594c72a1446137926d4c2aa04e345f798dcVendor (CNA)
Linux Linuxa425c82ff06cda5165e0de3de8c2a445ec1f863eVendor (CNA)
Linux Linuxb2a017bfcf565721918ec7355a373911d2f2a227Vendor (CNA)
Linux Linuxfc973ecd1a079b9a87c360478542f3a56dea085bVendor (CNA)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records