Resource exhaustion in Unrealircd

CVE-2026-90668

The webserver in UnrealIRCd 6.0.5 through 6.2.6 before 6.2.7 does not limit the number of HTTP request headers, which allows remote attackers to cause a denial of service (memory consumption and unresponsive server) via an HTTP request with an unlimited number of headers, if a websocket or JSON-RPC listener is enabled (disabled by default).

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.006 (47.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 47.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-90668: held from 0.006 to 0.006.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-90668?
CVE-2026-90668 is a high-severity vulnerability in Unrealircd, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 7.5/10. Published 2026-09-13.
How severe is CVE-2026-90668?
High severity. CVSS v3 base score is 7.5 out of 10.