Buffer overflow in Openwrt

CVE-2026-30872

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.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.011 (64.2th percentile), scored .

Low probability of exploitation in the next 30 days, but still tracked. 64th percentile — 64.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-30872: fell from 0.022 to 0.011.

EPSS over last 30 days · oldest: 0.022 · newest: 0.011 · change: -0.011

Affected products

  • Openwrt — versions >= 25.12.0-rc1, < 25.12.1, < 24.10.6

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-30872?
CVE-2026-30872 is a critical-severity vulnerability in Openwrt, classified under Stack-based Buffer Overflow. CVSS score: 9.8/10. Published 2026-03-19.
How severe is CVE-2026-30872?
Critical severity. CVSS v3 base score is 9.8 out of 10.