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

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Summary

CVECVE-2026-55490
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-07 22:16:54 UTC
Updated2026-07-10 17:37:00 UTC
DescriptionOpenWrt 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.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.006840000 probability, percentile 0.482480000 (date 2026-07-11)

Problem Types: CWE-191 | CWE-191 CWE-191: Integer Underflow (Wrap or Wraparound)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED6.5MEDIUMCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Openwrt Openwrt All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Openwrt Openwrt affected < 25.12.5 Not specified

References

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