Resource allocation without limits in UnrealIRCd
Priority MEDIUM 44CWE-770Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-770.
Summary
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).
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00582 48th percentileScored 2026-11-07
Fix Fixed UnrealIRCd (UnrealIRCd): 6.2.7
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| UnrealIRCd | UnrealIRCd | 6.0.5 to before 6.2.7 | 6.2.7 | Patch available | CNA |
- UnrealIRCd VendorUnrealIRCd Affected 6.0.5 to before 6.2.7 Fixed in 6.2.7 Patch available CNA
Remediation
- Fix · CNA UnrealIRCd (UnrealIRCd) Fixed in 6.2.7
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2026-90668
- 2026-10-03 Alias added: GHSA-fj9c-wr2v-556h
More UnrealIRCd vulnerabilities
- TI-2010-01989 UnrealIRCd 3.2.8.1, as distributed on certain mirror sites from November 2009 through… CVSS 2.0HIGH 7.5
- TI-2026-86760 UnrealIRCd labeled-response module allows command injection via label tag CVSS 3.1HIGH 8.6
- TI-2016-06143 The m_authenticate function in modules/m_sasl.c in UnrealIRCd before 3.2.10.7 and 4.x… CVSS 3.0HIGH 8.1
- TI-2023-27714 A buffer overflow in websockets in UnrealIRCd 6.1.0 through 6.1.3 before 6.1.4 allows an… CVSS 3.1HIGH 7.5
- TI-2009-04649 Buffer overflow in UnrealIRCd 3.2beta11 through 3.2.8, when allow::options::noident is… CVSS 2.0MEDIUM 6.8
- TI-2013-06048 UnrealIRCd 3.2.10 before 3.2.10.2 allows remote attackers to cause a denial of service… CVSS 2.0MEDIUM 5.0
Sources
- CVE-2026-90668 · CVE Program
- CVE-2026-90668 · NVD
- FIRST EPSS
- GHSA-fj9c-wr2v-556h · GitHub Advisory Database · CC BY 4.0
- CVE-2026-90668 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences