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NVD / CVE Program· CNA Linux

CVE-2025-40083: net/sched: sch_qfq: Fix null-deref in agg_dequeue

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: 0.20% (FIRST EPSS).
  • Fixed version: Linux Linux 1bed56f089f09b465420bf23bb32985c305cfc28, 3c2a8994807623c7655ece205667ae2cf74940aa, 6ff8e74c8f8a68ec07ef837b95425dfe900d060f; azl3 kernel 6.6.112.1-2 on Azure Linux 3.0 6.6.117.1-1.

Low priority for now. Upgrade to Linux Linux 1bed56f089f09b465420bf23bb32985c305cfc28, 3c2a8994807623c7655ece205667ae2cf74940aa, 6ff8e74c8f8a68ec07ef837b95425dfe900d060f; azl3 kernel 6.6.112.1-2 on Azure Linux 3.0 6.6.117.1-1 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_qfq: Fix null-deref in agg_dequeue To prevent a potential crash in agg_dequeue (net/sched/sch_qfq.c) when cl->qdisc->ops->peek(cl->qdisc) returns NULL, we check the return value before using it, similar to the existing approach in sch_hfsc.c. To avoid code duplication, the following changes are made: 1. Changed qdisc_warn_nonwc(include/net/pkt_sched.h) into a static inline function. 2. Moved qdisc_peek_len from net/sched/sch_hfsc.c to include/net/pkt_sched.h so that sch_qfq can reuse it. 3. Applied qdisc_peek_len in agg_dequeue to avoid crashing.

—No exploit Fix available
Published
Oct 29, 2025
Updated
Oct 19, 2026
EPSS
0.2% · 10th 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

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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.

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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

    • 3.8affected
    • 462dbc9101acd38e92eda93c0726857517a24bbd and later · before 71d84658a61322e5630c85c5388fc25e4a2d08b2affected · git
    • 462dbc9101acd38e92eda93c0726857517a24bbd and later · before 99fc137f178797204d36ac860dd8b31e35baa2dfaffected · git
    • 462dbc9101acd38e92eda93c0726857517a24bbd and later · before 1bed56f089f09b465420bf23bb32985c305cfc28affected · git
    • 462dbc9101acd38e92eda93c0726857517a24bbd and later · before 3c2a8994807623c7655ece205667ae2cf74940aaaffected · git
    • 462dbc9101acd38e92eda93c0726857517a24bbd and later · before 6ffa9d66187188e3068b5a3895e6ae1ee34f9199affected · git
    • 462dbc9101acd38e92eda93c0726857517a24bbd and later · before 6ff8e74c8f8a68ec07ef837b95425dfe900d060faffected · git
    • 462dbc9101acd38e92eda93c0726857517a24bbd and later · before dd831ac8221e691e9e918585b1003c7071df0379affected · git
    • before 3.8not affected · semver
    • 5.4.302 and later · up to and including 5.4.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:11linux-6.1before 6.1.159-1~deb11u16.1.159-1~deb11u1
Debian:12linuxbefore 6.1.159-16.1.159-1
Debian:13linuxbefore 6.12.57-16.12.57-1
Debian:14linuxbefore 6.16.3-16.16.3-1

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-2025-40081Oct 28, 2025 · perf: arm_spe: Prevent overflow in PERF_IDX2OFF()
    31Monitor
  • ← EarlierCVE-2023-7324Oct 29, 2025 · scsi: ses: Fix possible addl_desc_ptr out-of-bounds accesses
    32Monitor
  • Later →CVE-2025-40084Oct 29, 2025 · ksmbd: transport_ipc: validate payload size before reading handle
    28Monitor

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 Linux1bed56f089f09b465420bf23bb32985c305cfc28Vendor (CNA)
Linux Linux3c2a8994807623c7655ece205667ae2cf74940aaVendor (CNA)
Linux Linux6ff8e74c8f8a68ec07ef837b95425dfe900d060fVendor (CNA)
Linux Linux6ffa9d66187188e3068b5a3895e6ae1ee34f9199Vendor (CNA)
Linux Linux71d84658a61322e5630c85c5388fc25e4a2d08b2Vendor (CNA)
Linux Linux99fc137f178797204d36ac860dd8b31e35baa2dfVendor (CNA)
Linux Linuxdd831ac8221e691e9e918585b1003c7071df0379Vendor (CNA)
azl3 kernel 6.6.112.1-2 on Azure Linux 3.06.6.117.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.159-1 · Debian:12Package registry (OSV)
debian:linux-6.16.1.159-1~deb11u1 · Debian:11Package 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.

No history yet (it accumulates with the daily EPSS job).

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. Fix✗ → ✓

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References

Show all references (6 more)

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

All records