OpenWRT up to 24.10.5/25.12.0 match_ipv6_addresses stack-based overflow

Summaryinfo

A vulnerability was found in OpenWRT up to 24.10.5/25.12.0. It has been declared as critical. This impacts the function match_ipv6_addresses. Executing a manipulation can lead to stack-based overflow. This vulnerability is registered as CVE-2026-30872. It is possible to launch the attack remotely. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in OpenWRT up to 24.10.5/25.12.0. This vulnerability affects the function match_ipv6_addresses. The manipulation with an unknown input leads to a stack-based overflow vulnerability. The CWE definition for the vulnerability is CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

OpenWrt Project is a Linux operating system targeting embedded devices. In versions prior to 24.10.6 and 25.12.1, the mdns daemon has a Stack-based Buffer Overflow vulnerability in the match_ipv6_addresses function, triggered when processing PTR queries for IPv6 reverse DNS domains (.ip6.arpa) received via multicast DNS on UDP port 5353. During processing, the domain name from name_buffer is copied via strcpy into a fixed 256-byte stack buffer, and then the reverse IPv6 request is extracted into a buffer of only 46 bytes (INET6_ADDRSTRLEN). Because the length of the data is never validated before this extraction, an attacker can supply input larger than 46 bytes, causing an out-of-bounds write. This allows a specially crafted DNS query to overflow the stack buffer in match_ipv6_addresses, potentially enabling remote code execution. This issue has been fixed in versions 24.10.6 and 25.12.1.

The advisory is available at github.com. This vulnerability was named CVE-2026-30872 since 03/06/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details are known, but there is no available exploit.

Upgrading to version 24.10.6 or 25.12.1 eliminates this vulnerability. The upgrade is hosted for download at github.com.

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Productinfo

Name

• OpenWRT

Version

• 24.10.0
• 24.10.1
• 24.10.2
• 24.10.3
• 24.10.4
• 24.10.5
• 25.0
• 25.1
• 25.2
• 25.3
• 25.4
• 25.5
• 25.6
• 25.7
• 25.8
• 25.9
• 25.10
• 25.11
• 25.12.0

Website

• Product: https://github.com/openwrt/openwrt/

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