How severe is CVE-2025-25200?

CVE-2025-25200 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2025-25200 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-25200?

CVE-2025-25200 primarily affects Koajs Koa. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-25200?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-25200 have an EU (EUVD) identifier?

Yes. CVE-2025-25200 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-4086.

When was CVE-2025-25200 published?

CVE-2025-25200 was published on 2025-02-12 and last updated on 2026-06-17.

CVE-2025-25200

CVE-2025-25200 is a high-severity vulnerability in Koajs Koa with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-1333.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 9.2
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-4086
Weakness: CWE-1333
Affected product: Koajs Koa
Published: 2025-02-12
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2025-25200?: 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.
How severe is CVE-2025-25200?: CVE-2025-25200 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-25200 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-25200?: CVE-2025-25200 primarily affects Koajs Koa. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-25200?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-25200 have an EU (EUVD) identifier?: Yes. CVE-2025-25200 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-4086.
When was CVE-2025-25200 published?: CVE-2025-25200 was published on 2025-02-12 and last updated on 2026-06-17.

References

Affected products (4)

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:*:*

More vulnerabilities in Koajs Koa

CVE-2026-27959 — High (CVSS 7.5): Koa is middleware for Node.js using ES2017 async functions. Prior to versions 3.1.2 and 2.16.4, Koa's `ctx.hostname`…
CVE-2025-32379 — Medium (CVSS 5.0): Koa is expressive middleware for Node.js using ES2017 async functions. In koa < 2.16.1 and < 3.0.0-alpha.5, passing…
CVE-2025-62595 — Medium (CVSS 4.3): Koa is expressive middleware for Node.js using ES2017 async functions. In versions 2.16.2 to before 2.16.3 and 3.0.1 to…
CVE-2025-8129 — Low (CVSS 3.5): A vulnerability, which was classified as problematic, was found in KoaJS Koa up to 3.0.0. Affected is the function back…

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