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CVE-2022-36087 — OAuthLib vulnerable DoS when attacker provides malicious IPV6 URI

2026-09-28T18:24:56.346397+00:00

Affected: oauthlib

OAuthLib is an implementation of the OAuth request-signing logic for Python 3.6+. In OAuthLib versions 3.1.1 until 3.2.1, an attacker providing malicious redirect uri can cause denial of service. An attacker can also leverage usage of `uri_validate` functions depending where it is used. OAuthLib applications using OAuth2.0 provider support or use directly `uri_validate` are affected by this issue. Version 3.2.1 contains a patch. There are no known workarounds.

GHSA-3pgj-pg6c-r5p7 — OAuthLib vulnerable to DoS when attacker provides malicious IPV6 URI

2026-09-28T18:24:56.346518+00:00

Affected: PyPI: oauthlib

### Impact - Attacker providing malicious redirect uri can cause DoS to oauthlib's web application. - Attacker can also leverage usage of `uri_validate` functions depending where it is used.

_What kind of vulnerability is it? Who is impacted?_

Oauthlib applications using OAuth2.0 provider support or use directly `uri_validate` function.

### Patches _Has the problem been patched? What versions should users upgrade to?_

Issue fixed in 3.2.2 release.

### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_

The `redirect_uri` can be verified in web toolkit (i.e `bottle-oauthlib`, `django-oauth-toolkit`, ...) before oauthlib is called. A sample check if `:` is present to reject the request can prevent the DoS, assuming no port or IPv6 is fundamentally required.

### References Attack Vector: - Attacker providing malicious redirect uri: https://github.com/oauthlib/oauthlib/blob/d4bafd9f1d0eba3766e933b1ac598cbbf37b8914/oauthlib/oauth2/rfc6749/grant_types/base.py#L232 - Vulnerable `uri_validate` functions: https://github.com/oauthlib/oauthlib/blob/2b8a44855a51ad5a5b0c348a08c2564a2e197ea2/oauthlib/uri_validate.py

### PoC ```python is_absolute_uri("http://[:::::::::::::::::::::::::::::::::::::::]/path") ```

### Acknowledgement Special thanks to Sebastian Chnelik - PyUp.io

PYSEC-2022-269

2026-09-28T18:24:56.346606+00:00

Affected: PyPI: oauthlib