CVE-2026-55490

What it is

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.

At a glance

Exploitability

Can be exploited from the same network segment without logging in. High risk of service disruption.

Exploit odds

0.7% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-07 22:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-10 17:37 UTC Last updatedMost recent change to the record

Details

Published

2026-07-07 22:16 UTC

Last modified

2026-07-10 17:37 UTC

Exploit probability

0.7% · EPSS, next 30 days

Weakness

CWE-191

Record status

Analyzed

Affected

• Openwrt < 25.12.5

Attack profile CVSS 3.1 · 6.5

Attack vector

Adjacent network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High