CVE-2026-55490 MEDIUM

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

Vendor Openwrt
Product openwrt
Weakness CWE-191
Published July 7, 2026
Last update July 7, 2026

CVSS base score

6.5/10
Attack vector Adjacent
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

July 7, 2026 CVE published