CVE-2025-25200: Koa is expressive middleware for Node.js using ES2017 async functions

Q: How do I fix CVE-2025-25200?

koa: upgrade to 0.21.2, 1.7.1, 2.15.4. Exact commands for each OS are on this page.

Q: Is CVE-2025-25200 being exploited?

CVE-2025-25200 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2025-25200 affect?

CVE-2025-25200 affects koa. Severity is high (CVSS 7.5). 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 expl

Q: How urgent is CVE-2025-25200?

Priority 46/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2025-25200 is a high-severity flaw (CVSS 7.5) affecting koa. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 42%)
CISA exploited list	No
Weakness	CWE-1333
Published	2025-02-12
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: koajs

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-02-12 18:15 UTCPublished CVE record published
2026-06-17 09:00 UTCUpdated Record last modified

koajs koa UPGRADE

Affected: < 0.21.2 · >= 1.0.0 and < 1.7.1 · >= 2.0.0 and < 2.15.4 · 3.0.0 alpha0 · 3.0.0 alpha1 · 3.0.0 alpha2

Fixed in: 0.21.2, 1.7.1, 2.15.4

Safe to downgrade to: a release before 1.0.0

1. Check installed version

npm ls koa

2. UPGRADE to 0.21.2

npm install koa@">=0.21.2"

3. If no update is available yet, DOWNGRADE to a release before 1.0.0

npm view koa versions npm install koa@"<1.0.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-25200?

koa: upgrade to 0.21.2, 1.7.1, 2.15.4. Exact commands for each OS are on this page.

Is CVE-2025-25200 being exploited?

CVE-2025-25200 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-25200 affect?

CVE-2025-25200 affects koa. Severity is high (CVSS 7.5). 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 expl

How urgent is CVE-2025-25200?

Priority 46/100. High severity; Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

Related CVEs

CVE-2025-62595 MEDIUM 4.3 UPGRADE Koa is expressive middleware for Node.js using ES2017 async functions
CVE-2026-27959 HIGH 7.5 UPGRADE Koa is middleware for Node.js using ES2017 async functions
CVE-2025-8129 LOW 3.5 UPGRADE A vulnerability, which was classified as problematic, was found in KoaJS Koa up to 3.0.0
CVE-2025-32379 MEDIUM 5.0 UPGRADE Koa is expressive middleware for Node.js using ES2017 async functions

References

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