Integer overflow in Openwrt
CVE-2026-55490
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.
EPSS: 0.010 (59.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Openwrt — versions < 25.12.5
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-55490?
- CVE-2026-55490 is a medium-severity vulnerability in Openwrt, classified under Integer Underflow. CVSS score: 6.5/10. Published 2026-07-07.
- How severe is CVE-2026-55490?
- Medium severity. CVSS v3 base score is 6.5 out of 10.