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CVE-2026-90109· NVD / CVE Program· CNA Linux

net: sched: fix 32-bit backlog wrap in gred, bfifo and plug enqueue

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 3fb51b3960342bbee563543f8d33710fd0fb5a96, 4c660ee8c809637909f4f7eb1017f7b9401c75c4, 8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.

Low priority for now. Upgrade to Linux Linux 3fb51b3960342bbee563543f8d33710fd0fb5a96, 4c660ee8c809637909f4f7eb1017f7b9401c75c4, 8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes 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: fix 32-bit backlog wrap in gred, bfifo and plug enqueue gred_enqueue(), bfifo_enqueue() and plug_enqueue() admit a packet when the current backlog plus the packet length fits within the queue limit: sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (gred default VQ) gred_backlog+qdisc_pkt_len(skb) <= q->limit (gred configured VQ) sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit (bfifo) sch->qstats.backlog + skb->len <= q->limit (plug) sch->qstats.backlog and q->backlog are u32, and qdisc_pkt_len()/skb->len are unsigned int, so all sums are computed in 32 bits and wrap at 2^32. Once the true backlog exceeds 4 GiB the wrapped sum becomes small and admission keeps succeeding, so the queue grows without bound and the kernel can be driven to OOM. Promote the sums to u64 so admission stops once the true backlog exceeds the limit. The limit is u32, so the bounded queue stays below 2^32 and the stored u32 backlog never wraps. The bug can only be reproduced as root (albeit with ridiculous setup): attach a gred (or bfifo/plug) qdisc with a limit near 4 GiB, leaving the default VQ unconfigured (for gred), and drive >4 GiB of queued traffic (e.g. via a size table / stab to inflate qdisc_pkt_len, or sustained high-rate traffic). The u32 backlog+len sum wraps at 2^32, admission keeps succeeding, and the queue grows unboundedly to OOM.

—No exploit Fix available
Published
Sep 17, 2026
Updated
Oct 21, 2026
EPSS
0.2% · 9th 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%

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Noroxi analysis

What does it mean in your environment?

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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

    • 4.2affected
    • a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 and later · before c5ca77024812563fe15c4f7aa906791c3683e9fdaffected · git
    • a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 and later · before 3fb51b3960342bbee563543f8d33710fd0fb5a96affected · git
    • a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 and later · before 8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6affected · git
    • a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 and later · before d98b92f3d57976ae185238946ec5ea0be32195aaaffected · git
    • a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 and later · before 4c660ee8c809637909f4f7eb1017f7b9401c75c4affected · git
    • before 4.2not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver
    • 6.12.110 and later · up to and including 6.12.*not affected · semver
    • 6.18.52 and later · up to and including 6.18.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

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-2026-90107Sep 17, 2026 · net/smc: free pending qentry in smc_llc_flow_stop() before memset
    0Monitor
  • ← EarlierCVE-2026-90108Sep 17, 2026 · net/smc: free stashed qentry before overwrite in REQ_ADD_LINK to ADD_LINK transition
    0Monitor
  • Later →CVE-2026-90110Sep 17, 2026 · inetpeer: randomize RB-tree node comparison using SipHash
    37Monitor

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 Linux3fb51b3960342bbee563543f8d33710fd0fb5a96Vendor (CNA)
Linux Linux4c660ee8c809637909f4f7eb1017f7b9401c75c4Vendor (CNA)
Linux Linux8b2d8c70b969bf84f9e248bfaf2a7135129f2eb6Vendor (CNA)
Linux Linuxc5ca77024812563fe15c4f7aa906791c3683e9fdVendor (CNA)
Linux Linuxd98b92f3d57976ae185238946ec5ea0be32195aaVendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · 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. Fix✗ → ✓

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References

Show all references (4 more)

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

All records