VulnerabilityAnalyzed

CVE-2026-55490

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.

MEDIUM 6.5EPSS 0.68%

Does this matter?

Lower severity and a low EPSS score (0.68%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1: 6.5 MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.68% probability · 51th percentile
CISA KEV: Not listed
Weakness: CWE-191
Affected: openwrt/openwrt
Source: security-advisories@github.com

References

https://github.com/openwrt/openwrt/commit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5Patch
https://github.com/openwrt/openwrt/releases/tag/v25.12.5Release Notes
https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fwExploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.