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NVD / CVE Program· CNA Linux

CVE-2026-74739: net/sched: cls_u32: skip hash tables in u32_bind_class()

Noroxi assessment

Priority: Monitor (action score 31/100)

  • 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: 0.13% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 07f57c7c47459e9bc75186b3af0fc2bc5be72f89, 19d114b93c94bdef70496f26685c2a6b242f41b3, 31f26a95eeee926946809ac456c61a3217936a62; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 07f57c7c47459e9bc75186b3af0fc2bc5be72f89, 19d114b93c94bdef70496f26685c2a6b242f41b3, 31f26a95eeee926946809ac456c61a3217936a62; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1 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: cls_u32: skip hash tables in u32_bind_class() u32_walk() enumerates both struct tc_u_hnode and struct tc_u_knode through the walker callback. u32_bind_class() unconditionally casts the passed fh to tc_u_knode and accesses &n->res, so when fh is actually a tc_u_hnode, which has no tcf_result member, this results in a slab-out-of-bounds read of res->classid in tc_cls_bind_class(). The issue can be reproduced with the following commands: tc qdisc add dev lo root handle 1: hfsc tc class add dev lo parent 1: classid 1:1 hfsc sc rate 1000kbit tc filter add dev lo parent 1:1 protocol ip prio 1 u32 match u32 0 0 flowid 1:1 tc class add dev lo parent 1: classid 1:2 hfsc sc rate 2000kbit Fix this by skipping hash tables via the TC_U32_KEY(handle) check.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Aug 26, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 3th percentile
CWE
—

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
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.

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.

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When you'll hear from us

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

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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

    • 4.14affected
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before 43e1a952d534fc0e173b513a24b19ce99bb60974affected · git
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before 07f57c7c47459e9bc75186b3af0fc2bc5be72f89affected · git
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before ec5f3005586a785689fd568361b0c5925cb1548baffected · git
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before 19d114b93c94bdef70496f26685c2a6b242f41b3affected · git
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before 594a064d603202b9ee21e07679d854e5c1750cc4affected · git
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before 31f26a95eeee926946809ac456c61a3217936a62affected · git
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before e71f8e9ed6f311410b14741f6012afe01869c0faaffected · git
    • 07d79fc7d94e3f884b8b1c95aa615b202bb5e4c1 and later · before 6d3724e616faf952c3adcf8414fc21a828ef3709affected · git
    • before 4.14not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.105-16.12.105-1
Debian:14linuxbefore 7.1.10-17.1.10-1

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-2026-74735Aug 26, 2026 · l2tp: fix tunnel and session refcount leak on seq_file release
    0Monitor
  • ← EarlierCVE-2026-74736Aug 26, 2026 · net/sched: cls_bpf: reject dev-bound programs bound to a different device
    31Monitor
  • Later →CVE-2026-74740Aug 26, 2026 · net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain
    0Monitor

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 Linux07f57c7c47459e9bc75186b3af0fc2bc5be72f89Vendor (CNA)
Linux Linux19d114b93c94bdef70496f26685c2a6b242f41b3Vendor (CNA)
Linux Linux31f26a95eeee926946809ac456c61a3217936a62Vendor (CNA)
Linux Linux43e1a952d534fc0e173b513a24b19ce99bb60974Vendor (CNA)
Linux Linux594a064d603202b9ee21e07679d854e5c1750cc4Vendor (CNA)
Linux Linux6d3724e616faf952c3adcf8414fc21a828ef3709Vendor (CNA)
Linux Linuxe71f8e9ed6f311410b14741f6012afe01869c0faVendor (CNA)
Linux Linuxec5f3005586a785689fd568361b0c5925cb1548bVendor (CNA)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.107-1~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).

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

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • 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
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

—

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/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