CVE-2026-100351 kin-openapi: ValidationHandler security-requirement bypass via encoded-path operation confusion
Attackers can bypass authentication in kin-openapi by exploiting path decoding mismatches between validation and routing, accessing protected endpoints without credentials.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-100351?
CVE-2026-100351 is a high-severity authentication bypass vulnerability in getkin kin-openapi, published on 15 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
kin-openapi is a Go project for handling OpenAPI files. From 0.144.0 until 0.147.0, openapi3filter.ValidationHandler validates an operation selected from decoded URL.Path while a downstream gorilla/mux router configured with UseEncodedPath can dispatch a different operation selected from URL.RawPath. When a public exact route and a protected parameterized route use the same method and overlap after decoding, an unauthenticated remote request containing an encoded path separator can be validated as public and then dispatched to the protected handler without invoking the configured AuthenticationFunc. The reachable path parameter is constrained to an encoded representation that decodes to the public literal route, and proxies that canonicalize the URI before forwarding prevent this specific mismatch. This issue is fixed in version 0.147.0.
Which versions are affected by CVE-2026-100351?
2 open source packages ship an affected version, including github.com/getkin/kin-openapi.
| Package | Affected | Fixed in |
|---|---|---|
github.com/getkin/kin-openapi Go | From 0.144.0 | 0.147.0 |
github.com/getkin/kin-openapi Go | From 0.144.0 | 0.147.0 |
How do I fix CVE-2026-100351?
Upgrade github.com/getkin/kin-openapi to 0.147.0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-100351 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100351 exists.
Sources
Also known as CLEANSTART-2026-ZP83138, ECHO-5281-32ff-334d, GHSA-23vg-4cjm-66q5, MINI-339f-pcx8-mr64, MINI-372g-5w67-ghx3, MINI-46rp-3rvv-vj79 and 14 more.