Vulnerability-Lookup

CVE-2026-90668 (GCVE-0-2026-90668)

Vulnerability from cvelistv5 – Published: 2026-09-13 02:00 – Updated: 2026-09-14 18:13

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).

Severity

8.7 (High)


                        
                          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

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-14 18:13 UTC

CWE

CWE-770 - Allocation of Resources Without Limits or Throttling

Assigner

mitre mitre root

References

2 references

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

Impacted products

1 product

Vendor	Product	Version	CPE status
UnrealIRCd	UnrealIRCd	Affected: 6.0.5 , < 6.2.7 (semver) cpe:2.3:a:unrealircd:unrealircd::::::::

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-90668

Vulnerability from fkie_nvd - Published: 2026-09-13 02:17 - Updated: 2026-09-14 19:18

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	cve@mitre.org	https://forums.unrealircd.org/viewtopic.php?t=9483
	cve@mitre.org	https://www.unrealircd.org/

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
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    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "webserver"
          ],
          "product": "UnrealIRCd",
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          ],
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  ],
  "id": "CVE-2026-90668",
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          "role": "CISA Coordinator",
          "timestamp": "2026-09-14T18:13:05.650571Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-13T02:17:05.103",
  "references": [
    {
      "source": "cve@mitre.org",
      "url": "https://forums.unrealircd.org/viewtopic.php?t=9483"
    },
    {
      "source": "cve@mitre.org",
      "url": "https://www.unrealircd.org/"
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-770"
        }
      ],
      "source": "cve@mitre.org",
      "type": "Secondary"
    }
  ]
}

GHSA-FJ9C-WR2V-556H

Vulnerability from github – Published: 2026-09-13 03:30 – Updated: 2026-09-13 03:30

Details

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

8.7 (High)


                  
                    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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-90668"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-13T02:17:05Z",
    "severity": "HIGH"
  },
  "details": "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).",
  "id": "GHSA-fj9c-wr2v-556h",
  "modified": "2026-09-13T03:30:21Z",
  "published": "2026-09-13T03:30:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90668"
    },
    {
      "type": "WEB",
      "url": "https://forums.unrealircd.org/viewtopic.php?t=9483"
    },
    {
      "type": "WEB",
      "url": "https://www.unrealircd.org"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:A/V:X/RE:L/U:X",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-90668 (GCVE-0-2026-90668)

FKIE_CVE-2026-90668

GHSA-FJ9C-WR2V-556H

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Sightings

Nomenclature

Related by attack behaviour