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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.

PUBLISHED Reserved 2026-06-16 | Published 2026-07-07 | Updated 2026-07-08 | Assigner GitHub_M




MEDIUM: 6.5CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem types

CWE-191: Integer Underflow (Wrap or Wraparound)

Product status

< 25.12.5
affected

References

github.com/...penwrt/security/advisories/GHSA-9558-77jp-g3fw

github.com/...ommit/63c0767f3d02f7b10b0f0b5293366bd059a08ca5

github.com/openwrt/openwrt/releases/tag/v25.12.5

cve.org (CVE-2026-55490)

nvd.nist.gov (CVE-2026-55490)

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