Medium 6.5Published Jul 7, 2026

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

Updated under an hour ago (Oct 26, 2026, 2:30 PM ET)

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It affects openwrt. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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: 6.5 MEDIUM (v3.1, CNA)CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-191
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 8, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

openwrt openwrt openwrt:openwrt (from the name)	before 25.12.5	CNA record
openwrt openwrt openwrt:openwrt	before 25.12.5	NVD

References

References

https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fw	x-refsource-confirm, exploit, vendor-advisory
https://github.com/openwrt/openwrt/commit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5	x-refsource-misc, patch
https://github.com/openwrt/openwrt/releases/tag/v25.12.5	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.