CVE-2025-25200
Inefficient Regular Expression Complexity in koa
EPSS 0.50%
Description
### Summary 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. ### PoC Coming soon. ### Impact This is a Regex Denial-of-Service attack and causes memory exhaustion. The regex should be improved and empty values should not be allowed.
How to fix CVE-2025-25200
To remediate CVE-2025-25200, upgrade the affected package to a fixed version below.
- npm/koa—upgrade to 2.15.4 or later
Is CVE-2025-25200 being exploited?
Low — EPSS is 0.5%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 2.0.0, < 2.15.4
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |