CVE-2026-74564

Received Received - Intake

Hash Limit Rate Match Validation Flaw in Linux Kernel

Publication date: 2026-08-15

Last updated on: 2026-08-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_hashlimit: validate hashtable supports XT_HASHLIMIT_RATE_MATCH The XT_HASHLIMIT_RATE_MATCH flag mode changes the semantics of the dsthash_ent structure which represents an entry in the hashtable. There is a union area which uses a different layout to express the rate match mode. Update .checkentry path to validate the XT_HASHLIMIT_RATE_MATCH mode flag is requested by two or more different rules that refer to the same hashtable. Otherwise, uninitialized access to the burst field in the union is possible. Reject the use of the XT_HASHLIMIT_RATE_MATCH mode flag if set on by revision less than 3 too.

CVSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-19

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-74564

EUVD

EUVD-2026-59629

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	to 3 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves the netfilter xt_hashlimit module. It occurs when the XT_HASHLIMIT_RATE_MATCH flag is used incorrectly. This flag changes how entries in a hashtable are structured, and if multiple rules use the same hashtable with this flag, it can lead to uninitialized memory access in the burst field of the union structure.

Detection Guidance

This vulnerability affects the Linux kernel's netfilter xt_hashlimit module. Detection requires checking kernel versions and loaded modules. Use 'uname -r' to check kernel version and 'lsmod | grep xt_hashlimit' to verify if the module is loaded. Inspect iptables/nftables rules for XT_HASHLIMIT_RATE_MATCH usage with 'iptables -L -v' or 'nft list ruleset'.

Impact Analysis

This vulnerability could allow attackers to cause undefined behavior in the kernel, potentially leading to crashes, data corruption, or privilege escalation. Systems using affected netfilter rules with XT_HASHLIMIT_RATE_MATCH may be vulnerable.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a low-level kernel issue in the netfilter subsystem that could lead to uninitialized memory access, but no evidence suggests it impacts data protection, privacy, or security controls required by these regulations.

Mitigation Strategies

Update the Linux kernel to the latest patched version. If using custom iptables/nftables rules with XT_HASHLIMIT_RATE_MATCH, review and modify rules to avoid the vulnerable mode. Temporarily unload the xt_hashlimit module with 'rmmod xt_hashlimit' if immediate action is required.

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