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

Quick assessment

Affected
openwrt openwrt
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

OpenWrt是OpenWRT社区开源的一套针对嵌入式设备的Linux操作系统。 OpenWrt 25.12.5之前版本存在数字错误漏洞，该漏洞源于Emergency Access Daemon的handle_send_a()函数中存在整数下溢，可能导致未经身份验证的攻击者通过发送特制UDP数据包使守护进程崩溃。

CVSS 6.5 · Medium EPSS 0.68% · P51

Affected Version Matrix 1

VendorProduct Version RangeStatus
openwrt openwrt < 25.12.5 affected
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I. Basic Information for CVE-2026-55490

Vulnerability Information
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Vulnerability Title
OpenWrt: EAD Integer Underflow → Pre-Auth Denial of Service
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5
Vulnerability Title
OpenWrt 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
OpenWrt是OpenWRT社区开源的一套针对嵌入式设备的Linux操作系统。 OpenWrt 25.12.5之前版本存在数字错误漏洞，该漏洞源于Emergency Access Daemon的handle_send_a()函数中存在整数下溢，可能导致未经身份验证的攻击者通过发送特制UDP数据包使守护进程崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
openwrt openwrt < 25.12.5 -

II. Public POCs for CVE-2026-55490

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III. Intelligence Information for CVE-2026-55490

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Patches & Fixes for CVE-2026-55490 (1)

Vendor Advisories for CVE-2026-55490 (1)

Vendor Pages for CVE-2026-55490 (1)

IV. Related Vulnerabilities

Same product: openwrt
Same vendor: openwrt
Same weakness: CWE-191

V. Comments for CVE-2026-55490

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