CVE-2026-55490 OpenWrt: EAD Integer Underflow → Pre-Auth Denial of Service
An unauthenticated attacker can crash the Emergency Access Daemon via a crafted UDP packet due to an integer underflow, causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-55490?
CVE-2026-55490 is a medium-severity vulnerability in Openwrt Openwrt, published on 7 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-191
Which versions are affected by CVE-2026-55490?
It affects 1 product.
Products include Openwrt Openwrt.
How do I fix CVE-2026-55490?
No fix has been published for CVE-2026-55490 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-55490 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-55490 exists.
Other vulnerabilities in Openwrt Openwrt
- CVE-2020-28951 Use after free in n/a
- CVE-2026-62948 Cross-site scripting in openwrt
- CVE-2026-30871 OpenWrt Project has Stack-based Buffer Overflow in DNS PTR Query
- CVE-2026-30872 OpenWrt Project has a Stack-based Buffer Overflow vulnerability via IPv6 reverse DNS lookup
- CVE-2021-28961 Command injection in n/a
Sources
Also known as GHSA-9558-77jp-g3fw.