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Vulnerability ID

CVE-2026-31421

AI Exploitable

Null pointer dereference in net/sched/cls_fw

ProductLinux kernel

CVSS 3.1Medium5.5

EPSS0.12%

Has public PoCNo

AI Exploitability

A working PoC was successfully generated by AI

Working AI PoC: Yes
Cheapest run: $18.08
Fastest run: 1.8 hr

Model Matrix Capability Breakdown Vulnerability Details Timeline Community

Model Matrix Capability Breakdown Vulnerability Details Timeline Community

Overview

net/sched: cls_fw: fix NULL pointer dereference on shared blocks The old-method path in fw_classify() calls tcf_block_q() and dereferences q->handle. Shared blocks leave block->q NULL, causing a NULL deref when an empty cls_fw filter is attached to a shared block and a packet with a nonzero major skb mark is classified.

CWE: CWE-476
Weakness: NULL Pointer Dereference
Component: net/sched/cls_fw
Impact: Not stated
Published: 2026-04-13
Fixed version: 7.0

Risk factors

In-the-WildNot observed

CISA KEVNot listed

Public ExploitNone known

Ransomware useNone known

Severity

CVSS 3.1Only version published

5.5Medium

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

Exploitability

Attack VectorLocal

ComplexityLow

Privileges RequiredLow

User InteractionNone

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

EPSS

Chance of exploitation in the next 30 days

0.12%

SSVC

Stakeholder-specific vulnerability categorization

Not scored. CISA publishes an SSVC decision for a subset of CVEs.