CVE-2026-55490 — Security Box Score

CVE · referencelatest edition

Reference page — cumulative record through Wednesday, August 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-55490MEDIUM

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

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   A   L   N   N  U  N  N  H    6.5   .0099   59.7     —

AFFECTED
  Product  Versions     Fixed
  openwrt  < 25.12.5 –  —

TIMELINE
  Jun 16  Reserved by GitHub_M
  Jul 7   EXPLOIT PUBLISHED — CVE-2026-55490 (openwrt). Public exploit reference added.
  Jul 7   Published (CNA: GitHub_M)

CWE-191 · CNA: GitHub_M · CVSS v3.1 · 3 references · NVD status: Analyzed

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
June 16, 2026	Reserved	Reserved by GitHub_M
July 7, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-55490 (openwrt). Public exploit reference added.
July 7, 2026	Published	Published (CNA: GitHub_M)

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
openwrt	openwrt	—	< 25.12.5	—

Weaknesses

CWE-191

References (3)

https://github.com/openwrt/openwrt/commit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5 [Patch]
https://github.com/openwrt/openwrt/releases/tag/v25.12.5 [Release Notes]
https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fw [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-55490 at cve.org

Vendors: openwrt

Weaknesses: CWE-191

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-55490 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Wednesday, August 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.