Description
Koa is expressive middleware for Node.js using ES2017 async functions. Prior to versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3, Koa uses an evil regex to parse the `X-Forwarded-Proto` and `X-Forwarded-Host` HTTP headers. This can be exploited to carry out a Denial-of-Service attack. Versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3 fix the issue.
Published: 2025-02-12
Score: 9.2 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
EUVD EUVD EUVD-2025-4086 Koa is expressive middleware for Node.js using ES2017 async functions. Prior to versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3, Koa uses an evil regex to parse the `X-Forwarded-Proto` and `X-Forwarded-Host` HTTP headers. This can be exploited to carry out a Denial-of-Service attack. Versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3 fix the issue.
Github GHSA Github GHSA GHSA-593f-38f6-jp5m Inefficient Regular Expression Complexity in koa
History

Tue, 20 Jan 2026 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Koajs
Koajs koa
CPEs cpe:2.3:a:koajs:koa:*:*:*:*:*:node.js:*:*
cpe:2.3:a:koajs:koa:3.0.0:alpha0:*:*:*:node.js:*:*
cpe:2.3:a:koajs:koa:3.0.0:alpha1:*:*:*:node.js:*:*
cpe:2.3:a:koajs:koa:3.0.0:alpha2:*:*:*:node.js:*:*
Vendors & Products Koajs
Koajs koa
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

 cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Sat, 12 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00126}

 epss

{'score': 0.0014}

Fri, 11 Jul 2025 13:45:00 +0000

Type Values Removed Values Added
Metrics epss

{'score': 0.00152}

 epss

{'score': 0.00126}

Sat, 22 Feb 2025 02:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

 cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

threat_severity

Low

Fri, 21 Feb 2025 15:15:00 +0000

Type Values Removed Values Added
Metrics threat_severity

Critical

 cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

Fri, 21 Feb 2025 02:00:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Critical

Wed, 12 Feb 2025 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Wed, 12 Feb 2025 18:15:00 +0000

Type Values Removed Values Added
Description Koa is expressive middleware for Node.js using ES2017 async functions. Prior to versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3, Koa uses an evil regex to parse the `X-Forwarded-Proto` and `X-Forwarded-Host` HTTP headers. This can be exploited to carry out a Denial-of-Service attack. Versions 0.21.2, 1.7.1, 2.15.4, and 3.0.0-alpha.3 fix the issue.
Title Koa has Inefficient Regular Expression Complexity
Weaknesses CWE-1333
References
Metrics cvssV4_0

{'score': 9.2, '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:H'}

Subscriptions

Koajs Koa
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2025-02-12T19:29:10.232Z

Reserved: 2025-02-03T19:30:53.400Z

Link: CVE-2025-25200

cve-icon Vulnrichment

Updated: 2025-02-12T19:29:02.600Z

cve-icon NVD

Status : Analyzed

Published: 2025-02-12T18:15:28.110

Modified: 2026-01-20T14:42:45.760

Link: CVE-2025-25200

cve-icon Redhat

Severity : Low

Publid Date: 2025-02-12T17:59:04Z

Links: CVE-2025-25200 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses