Medium severity · published Jul 7, 2026
CVE-2026-55490
OpenWrt: EAD Integer Underflow → Pre-Auth Denial of Service
6.5
CVSS
0.7%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.7% · higher than 52% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
OP
openwrt · openwrt
< 25.12.5 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55490
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55490
Patch
https://github.com/openwrt/openwrt/commit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5
Release Notes
https://github.com/openwrt/openwrt/releases/tag/v25.12.5
Exploit
https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fw
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