How severe is CVE-2025-25200?

No CVSS score has been assigned to CVE-2025-25200 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-25200?

CVE-2025-25200 affects the following packages: koa (npm), koa (npm), koa (npm), koa (npm). Ecosystems affected: npm.

How do I fix CVE-2025-25200?

Update koa to 2.15.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-25200 is resolved across your whole dependency graph.

How do I detect CVE-2025-25200 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for koa. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2025-25200 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2025-25200?

O3 pinpoints whether CVE-2025-25200 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2025-25200 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-25200 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is CVE-2025-25200?

CVE-2025-25200 is classified as CWE-1333 (CWE-1333). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-25200 published, and has it been updated?

CVE-2025-25200 was published on February 12, 2025 and was last updated on July 15, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

CVE-2025-25200

Fix: koajs/koa@5054af6

CVE-2025-25200 is a CWE-1333 vulnerability in koa. O3 Security confirms whether CVE-2025-25200 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Koa has Inefficient Regular Expression Complexity

Also known asGHSA-593f-38f6-jp5m

Published

Feb 12, 2025

Updated

Jul 15, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Real-World Exposure

4 pkgs affected

📦koa📦koa📦koa📦koa

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects npm packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`koa`	≥ 2.0.0&&< 2.15.4	2.15.4
📦npm	`koa`	≥ 3.0.0-alpha.0&&< 3.0.0-alpha.3	3.0.0-alpha.3
📦npm	`koa`	≥ 1.0.0&&< 1.7.1	1.7.1
📦npm	`koa`	all versions	0.21.2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for koa. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update koa to 2.15.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-25200 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-25200 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2025-25200. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

Is CVE-2025-25200 in your dependencies?

O3 detects CVE-2025-25200 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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