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Vulnerabilities

Vulnerability · CVE-2026-100351

kin-openapi is a Go project for handling OpenAPI files.

Published Oct 15, 2026 · catalog updated Oct 15, 2026 · kin-openapi is a Go

Check if you run it

No confirmed exploitation is on record for CVE-2026-100351. EPSS is 0.49%. Act only if a listed version of kin-openapi is a Go is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (kin-openapi is a Go).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.49%
Remediation
Version ranges on file
Affected products
go github.com/getkin/kin-openapi · golang github.com

## Summary validates requests with kin-openapi's legacy router, which selects an OpenAPI operation from the decoded . The method is documented as implementing , but a downstream gorilla/mux router configured with selects its handler from the encoded representation ( ). An unauthenticated request such as can therefore be validated as an intentionally public operation ( ) and then dispatched to a protected operation ( ). The configured, rejecting is never invoked, and the protected downstream handler runs. This is distinct from GHSA-r277-6w6q-xmqw. The behavior below uses an explicit authentication callback that rejects missing credentials and remains reproducible after the v0.144.0 fix for the unsafe default callback. ## Affected products - Product: - Component: - Confirmed post-GHSA affected releases: v0.144.0, v0.145.0, and v0.146.0 - Reporter attestation: each listed release was checked out separately, the attached single-file test was copied into , and that test passed; maintainers should independently confirm the version range - Confirmed affected development revision: - v0.143.0 also reproduces this mechanism, but GHSA-r277-6w6q-xmqw already provides a simpler bypass on that release; the distinct post-fix claim starts at v0.144.0 - Earlier releases: not tested; please treat the introduction boundary as unknown ## Security impact An unauthenticated remote requester can reach a handler whose OpenAPI operation requires authentication when all of the following are true: 1. the application uses as the security gate; 2. the downstream router preserves and interprets an encoded path, such as gorilla/mux with ; 3. a public exact route and a protected parameterized route overlap after decoding; 4. the public and protected operations expose the same HTTP method; 5. the protected handler relies on the validation layer's security decision. The protected operation's path-parameter value is constrained: it is an encoded representation that decodes to a public literal path (

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • go github.com/getkin/kin-openapi>= 0.144.0, < 0.147.0
  • go github.com/getkin/kin-openapi>=0.144.0 <0.147.0
  • golang github.comversion unspecified

How to fix CVE-2026-100351

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-100351. EPSS is 0.49%. Act only if a listed version of kin-openapi is a Go is installed.

Which versions are affected?

Compare what you have installed with >= 0.144.0, < 0.147.0, >=0.144.0 <0.147.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-289; CWE-436. EPSS 0.49%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 15, 2026 · NIST NVD

    Detected

    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 afte

  2. Oct 15, 2026 · NIST NVD

    Updated

    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 afte

  3. Oct 15, 2026 · GitHub Advisory Database

    Updated

    ## Summary validates requests with kin-openapi's legacy router, which selects an OpenAPI operation from the decoded . The method is documented as implementing , but a downstream gorilla/mux router configured with selects its handler from the encoded representation ( ). An unauthenticated request such as can therefore be validated as an intentionally public operation ( ) and then dispatched to a pr

Sources

  • CVE.orgVulnerability recordCVE-2026-100351

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-100351

    30-day exploitation probability 0.5%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-23vg-4cjm-66q5

    kin-openapi: ValidationHandler security-requirement bypass via encoded-path operation confusion

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-100351

    openapi3filter.ValidationHandler.Middleware validates requests with kin-openapi's legacy router, which selects an OpenAPI operation from the decoded URL.Path. The method is documented as implementing gorilla/mux.MiddlewareFunc, but a downstream gorilla/mux router configured with UseEncodedPath() selects its handler from the encoded representation (URL.RawPath). An unauthenticated request such as /

    advisories.gitlab.com
  • GitLab Advisory DatabasePackage advisorygo/github.com/getkin/kin-openapi/CVE-2026-100351.yml

    validates requests with + kin-openapi's\nlegacy router, which selects an OpenAPI operation from the decoded + . The\nmethod is documented as implementing , + but a downstream\ngorilla/mux router configured with selects + its handler from the\nencoded representation ( ).\n\nAn unauthenticated + request such as can therefore be validated as an\nintentionally +

    gitlab.com
  • NIST NVDVulnerability recordCVE-2026-100351

    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 selec

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.