CVE-2026-5172

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Heap Out-of-Bounds Read in Dnsmasq DNS Response Handling

Publication date: 2026-05-11

Last updated on: 2026-06-30

Assigner: CERT/CC

Description

A buffer overflow in dnsmasq’s extract_addresses() function allows an attacker to trigger a heap out-of-bounds read and crash by exploiting a malformed DNS response, enabling extract_name() to advance the pointer past the record’s end.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-05-11

Last Modified

2026-06-30

Generated

2026-07-11

AI Q&A

2026-05-11

EPSS Evaluated

2026-07-10

NVD

CVE-2026-5172

EUVD

EUVD-2026-29156

Affected Vendors & Products

Vendor	Product	Version / Range
the_dnsmasq_project	dnsmasq	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-125	The product reads data past the end, or before the beginning, of the intended buffer.

Attack-Flow Graph

Mitigation Strategies

To mitigate the vulnerability CVE-2026-5172 in dnsmasq, you should update dnsmasq to the patched version 2.92rel2 or later, which includes fixes for this and other related vulnerabilities.

The patched version 2.92rel2 is available from the official dnsmasq website and has been incorporated into various package repositories, including NixOS.

Applying this update promptly will address the buffer overflow issue in the extract_addresses() function and prevent potential heap out-of-bounds reads and crashes caused by malformed DNS responses.

Executive Summary

This vulnerability is a buffer overflow in the extract_addresses() function of dnsmasq. It allows an attacker to cause a heap out-of-bounds read and crash the program by sending a malformed DNS response. The issue arises because the extract_name() function advances the pointer beyond the end of the DNS record.

Impact Analysis

The vulnerability can lead to a crash of the dnsmasq service due to a heap out-of-bounds read triggered by a malformed DNS response. This can cause denial of service, potentially disrupting network services that rely on dnsmasq for DNS resolution.

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