CVE-2026-55490OpenWrt: EAD Integer Underflow → Pre-Auth Denial of Service

Description

OpenWrt is a Linux operating system targeting embedded devices. Before v25.12.5, an integer underflow in handle_send_a() of the Emergency Access Daemon allows any unauthenticated attacker on the local network to crash the daemon by sending a single crafted UDP packet. The message length underflows before a bounds check and is then passed to memcpy as a very large size. This issue is fixed v25.12.5.

Data: CVE.org, NVD, CISA KEV, FIRST EPSS, Ubuntu. Published as the sources state it, in English.

Affected products and versions

References and patches

• https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fw ExploitVendor Advisory
• https://github.com/openwrt/openwrt/commit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5 Patch
• https://github.com/openwrt/openwrt/releases/tag/v25.12.5 Release Notes