CVE-2026-55490 json
OpenWrt: EAD Integer Underflow → Pre-Auth Denial of Service
published 2026-07-07 4 mo ago modified 2026-07-10 3 mo ago also EUVD-2026-42110
- cvss
- 6.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 52%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- openwrt openwrt 25.12.5
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 4 mo ago
Exploit prediction
0.68% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/openwrt/openwrt/security/advisories/GHSA-9558-77jp-g3fw referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 6.5 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
- openwrt openwrt
Classification
- Weakness
-
- CWE-191 Integer Underflow (Wrap or Wraparound)
References
Sources
- CVE List CVE-2026-55490
- NVD CVE-2026-55490
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