CVE-2026-90668 Denial of service in UnrealIRCd
Remote attackers can cause denial of service via excessive HTTP headers if websocket or JSON-RPC listeners are enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-90668?
CVE-2026-90668 is a high-severity denial of service vulnerability in UnrealIRCd, published on 13 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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).
Weakness: CWE-770
Which versions are affected by CVE-2026-90668?
How do I fix CVE-2026-90668?
No fix has been published for CVE-2026-90668 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-90668 being exploited?
There is no known exploitation of CVE-2026-90668 in the wild and no public exploit code.
Sources
Also known as GHSA-fj9c-wr2v-556h.