kin-openapi: Authentication Bypass by Alternate Name
CVE-2026-100351 is a high-severity authentication bypass by alternate name vulnerability in kin-openapi from Getkin, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected kin-openapi versions: >= 0.144.0, < 0.147.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.49% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of kin-openapi you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Getkin | kin-openapi | >= 0.144.0, < 0.147.0 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (github.com).
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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authentication Bypass by Alternate Name
The product performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.
How developers prevent this class of flaw
- Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
More Authentication Bypass by Alternate Name vulnerabilities (CWE-289)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
References
Patches and release notes
Other vulnerabilities in kin-openapi
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 8.2 High severity
- 8.7 High severity
Recent Authentication Bypass by Alternate Name vulnerabilities
- 8.7 High severity
- 9.8 Critical severity
- 8.1 High severity
- 9.8 Critical severity
- 8.1 High severity
- 9.8 Critical severity
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