CVE-2026-55490
OpenWrt: EAD Integer Underflow → Pre-Auth Denial of Service
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.
INFO
Published Date :
July 7, 2026, 10:16 p.m.
Last Modified :
July 10, 2026, 5:37 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Update OpenWrt to version 25.12.5 or later.
- Apply the security patch provided by the vendor.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-55490.
| URL | Resource |
|---|---|
| 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 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55490 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-55490
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-55490 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55490 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 10, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:o:openwrt:openwrt:*:*:*:*:*:*:*:* versions up to (excluding) 25.12.5 Added Reference Type GitHub, Inc.: https://github.com/openwrt/openwrt/commit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/openwrt/openwrt/releases/tag/v25.12.5 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fw Types: Exploit, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 08, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-55490', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-08T13:51:49.570163Z'} -
New CVE Received by [email protected]
Jul. 07, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'openwrt', 'product': 'openwrt', 'versions': [{'status': 'affected', 'version': '< 25.12.5'}]}] Added 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. Added CVSS V3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-191 Added Reference https://github.com/openwrt/openwrt/commit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5 Added Reference https://github.com/openwrt/openwrt/releases/tag/v25.12.5 Added Reference https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fw