🛡️ CVE-2026-55490 — openwrt

🟡 CVSS 6.5 — Medium ⚠️ Exploit Public CWE-191 NVD
6.5
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached from an adjacent network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Weakness class

CVE-2026-55490 is classified as CWE-191: Integer Underflow. A subtraction drops below the minimum for the type and wraps, yielding an unexpectedly large value.

Affected software

CVE-2026-55490 is recorded against 1 package.

  • openwrt (fixed in 25.12.5)

Timeline and source

Published on 7 July 2026 and last revised on 10 July 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
github.com

Details

Severity MEDIUM
CVSS Score 6.5
CVSS Vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE CWE-191
Public Exploit ⚠️ Yes
Source NVD
Published 2026-07-07
Updated 2026-08-11
Modified 2026-07-10

Affected Packages

Software From version Fixed in
openwrt — 25.12.5

Similar Threats

Exploit Protection

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