OpenWrt up to 25.12.4 Emergency Access Daemon handle_send_a integer underflow

CVSS Meta Temp Score
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CTI Interest Score
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7.2$0-$5k0.57

Summaryinfo

A vulnerability was found in OpenWrt up to 25.12.4. It has been classified as critical. Affected by this vulnerability is the function handle_send_a of the component Emergency Access Daemon. This manipulation causes integer underflow. This vulnerability is tracked as CVE-2026-55490. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in OpenWrt up to 25.12.4 and classified as critical. Affected by this vulnerability is the function handle_send_a of the component Emergency Access Daemon. The manipulation with an unknown input leads to a integer underflow vulnerability. The CWE definition for the vulnerability is CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. As an impact it is known to affect availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-55490 since 06/17/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available.

Upgrading to version 25.12.5 eliminates this vulnerability.

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Productinfo

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Integer underflow
CWE: CWE-191 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: OpenWrt 25.12.5

Timelineinfo

06/17/2026 CVE reserved
07/07/2026 +20 days VulDB entry created
07/08/2026 +0 days Advisory disclosed
07/08/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-55490 (🔒)
GCVE (CVE): GCVE-0-2026-55490
GCVE (VulDB): GCVE-100-376717

Entryinfo

Created: 07/08/2026 00:16
Changes: 07/08/2026 00:16 (53)
Complete: 🔍
Cache ID: 216::103

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