What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-07-07 · updated 2026-07-10
• Weakness: CWE-191

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.

Affected products

• openwrt: before 25.12.5 — fixed in 25.12.5

How to fix

Upgrade to a fixed version: openwrt 25.12.5. Check the vendor advisory for mitigations.

References

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

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