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NVD / CVE Program· CNA Linux

CVE-2026-80630: net/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.75% (FIRST EPSS); higher than 55.5% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 0500af8630c3253f0dde879bd3a73a06bb2f2b3f, 097f6fc7b1ae362dd7a9444b2572162fda73b284, 20dd591d8f951e1e6aca5052be8785e6181055e2.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0500af8630c3253f0dde879bd3a73a06bb2f2b3f, 097f6fc7b1ae362dd7a9444b2572162fda73b284, 20dd591d8f951e1e6aca5052be8785e6181055e2 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_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen Whenever fq_codel drops packets during peek, it calls qdisc_tree_reduce_backlog. An issue arises because it calls qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops to zero, but peek returns an skb, the parent's qlen_notify callback will be executed even though fq_codel still has 1 packet on the queue and, thus, will mistakenly deactivate the parent's class causing issues like a recent report [1] and a wild memory access in qfq: [ 29.371146][ T360] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI [ 29.371666][ T360] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127] [ 29.371987][ T360] CPU: 6 UID: 0 PID: 360 Comm: tc Not tainted 7.1.0-rc5-00285-gc530e5b2dbc6-dirty #82 PREEMPT(full) [ 29.372384][ T360] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 29.372620][ T360] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:1029 (discriminator 2) include/linux/list.h:1043 (discriminator 2) net/sched/sch_qfq.c:1369 (discriminator 2) net/sched/sch_qfq.c:1395 (discriminator 2)) sch_qfq [ 29.373544][ T360] RSP: 0018:ffff888102417370 EFLAGS: 00010216 [ 29.373800][ T360] RAX: 0000000000000000 RBX: ffff88811224d568 RCX: dffffc0000000000 [ 29.374079][ T360] RDX: 1ffff11021fe1543 RSI: ffff88810ff0aa00 RDI: dffffc0000000000 [ 29.374368][ T360] RBP: ffff88811224c280 R08: dead000000000122 R09: 1bd5a00000000024 [ 29.374649][ T360] R10: fffffbfff7940329 R11: fffffbfff7940329 R12: 0000000000000000 [ 29.374926][ T360] R13: dead000000000100 R14: ffff88811224d580 R15: ffff88811224d578 [ 29.375207][ T360] FS: 00007f5b794e5780(0000) GS:ffff88815d1e9000(0000) knlGS:0000000000000000 [ 29.375545][ T360] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.375823][ T360] CR2: 000055ffb091f000 CR3: 000000010a305000 CR4: 0000000000750ef0 [ 29.376103][ T360] PKRU: 55555554 [ 29.376258][ T360] Call Trace: [ 29.376401][ T360] <TASK> ... [ 29.376885][ T360] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq [ 29.377074][ T360] qdisc_reset (net/sched/sch_generic.c:1057) [ 29.377414][ T360] __qdisc_destroy (net/sched/sch_generic.c:1096) [ 29.377600][ T360] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159) [ 29.378593][ T360] tc_get_qdisc (net/sched/sch_api.c:1528 net/sched/sch_api.c:1556) Fix this by only calling qdisc_tree_reduce_backlog in peek after the qlen is restored. [1] http://lore.kernel.org/netdev/CAN2cbVe79oj0O9==m4+4x3v+O+qzRagA=2=wkrp9i9=CqYvyZA@mail.gmail.com/

Published
Aug 28, 2026
Updated
Oct 16, 2026
EPSS
0.7% · 55th percentile
CWE
—

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.7%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • 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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  • when exploit code appears or is weaponized
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  • when EPSS rises 20 points in a week

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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

    • 7a742a9506849d1c1aa71e36c89855ceddc7d58e, e73c838c80dccb9e4f19becc11d9f3cb4a27d483, a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31, 6.15affected
    • cc71a757da78dd4aa1b4a9b19cb011833730ccf2 and later · before 3e515188393e62a718ccebee651ee74514104ff6affected · git
    • eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450 and later · before 20dd591d8f951e1e6aca5052be8785e6181055e2affected · git
    • 829c49b6b2ff45b043739168fd1245e4e1a91a30 and later · before 94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80affected · git
    • 2f9761a94bae33d26e6a81b31b36e7d776d93dc1 and later · before acc08a0c7f37ebb1901144e03a7cba7d4afd9203affected · git
    • 4d55144b12e742404bb3f8fee6038bafbf45619d and later · before 7c09843fd2b44d9bf0de798683861d1aecd62a08affected · git
    • 342debc12183b51773b3345ba267e9263bdfaaef and later · before 0500af8630c3253f0dde879bd3a73a06bb2f2b3faffected · git
    • 342debc12183b51773b3345ba267e9263bdfaaef and later · before af54df2f44d9605614bc7ed96640302a240a9a62affected · git
    • 342debc12183b51773b3345ba267e9263bdfaaef and later · before 097f6fc7b1ae362dd7a9444b2572162fda73b284affected · 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-2026-80628Aug 28, 2026 · ALSA: seq: oss: Serialize readq reset state with q->lock
    31Monitor
  • ← EarlierCVE-2026-80629Aug 28, 2026 · octeontx2-af: npc: Fix size of entry2cntr_map
    0Monitor
  • Later →CVE-2026-80631Aug 28, 2026 · btrfs: lzo: reject compressed segment that overflows the compressed input
    30Monitor

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 Linux0500af8630c3253f0dde879bd3a73a06bb2f2b3fVendor (CNA)
Linux Linux097f6fc7b1ae362dd7a9444b2572162fda73b284Vendor (CNA)
Linux Linux20dd591d8f951e1e6aca5052be8785e6181055e2Vendor (CNA)
Linux Linux3e515188393e62a718ccebee651ee74514104ff6Vendor (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 Linux6.14Vendor (CNA)
Linux Linux6.15Vendor (CNA)
Linux Linux6.6.145Vendor (CNA)
Linux Linux7c09843fd2b44d9bf0de798683861d1aecd62a08Vendor (CNA)
Linux Linux94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80Vendor (CNA)
Linux Linuxacc08a0c7f37ebb1901144e03a7cba7d4afd9203Vendor (CNA)
Linux Linuxaf54df2f44d9605614bc7ed96640302a240a9a62Vendor (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+1% in 7 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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

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