CVE-2026-12969
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Out-of-Bounds Read in Dnsmasq DNS Response Parsing

Publication date: 2026-06-23

Last updated on: 2026-06-23

Assigner: Red Hat, Inc.

Description
An out-of-bounds read vulnerability exists in dnsmasq's find_soa() function in src/rfc1035.c. When parsing NS section records, extract_name() is called with extrabytes=0, failing to validate that 10 additional bytes exist for fixed-length DNS record fields. A remote attacker controlling a DNS zone can exploit this via a crafted NXDOMAIN response to cause a 10-byte heap out-of-bounds read, potentially accessing stale data from prior transactions.
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Meta Information
Published
2026-06-23
Last Modified
2026-06-23
Generated
2026-06-23
AI Q&A
2026-06-23
EPSS Evaluated
N/A
NVD
CVE-2026-12969
EUVD
EUVD-2026-38449
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
the_isc bind *
the_isc dnsmasq 2.93rc1
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.
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Executive Summary

CVE-2026-12969 is an out-of-bounds read vulnerability in dnsmasq's find_soa() function located in src/rfc1035.c. The problem occurs when parsing NS section records in NXDOMAIN or NODATA DNS responses. The function extract_name() is called with extrabytes=0, which only checks if the DNS name fits within the packet but fails to verify that 10 additional bytes exist for fixed-length DNS record fields such as type, class, TTL, and rdlen.

Because of this, the code reads 10 bytes beyond the valid packet boundary unconditionally, potentially accessing stale heap data from previous DNS transactions. An attacker controlling a DNS zone can exploit this by sending a specially crafted NXDOMAIN response that causes this out-of-bounds read.

Although the over-read usually stays within dnsmasq's over-allocated packet buffer, reducing the chance of a crash, it still exposes data outside the logical packet boundary.

Impact Analysis

This vulnerability allows a remote attacker who controls a DNS zone to cause dnsmasq to read 10 bytes beyond the intended packet boundary, potentially exposing stale heap data from previous DNS transactions.

While the risk of a crash is low due to dnsmasq's over-allocated buffer, the exposure of stale data could lead to information disclosure, which might be leveraged in further attacks depending on the nature of the leaked data.

Mitigation Strategies

The vulnerability in dnsmasq's find_soa() function was fixed in dnsmasq version 2.93rc1.

To mitigate this vulnerability, you should upgrade dnsmasq to version 2.93rc1 or later.

Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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