Python · Python Oic · CVE-2020-26244
**Name of the Vulnerable Software and Affected Versions**
Python oic versions prior to 1.2.1
**Description**
The issue affects client implementations using the Python oic library, a Python OpenID Connect implementation. There are several related cryptographic issues:
1) The IdToken signature algorithm was not checked automatically, but only if the expected algorithm was passed in as a kwarg.
2) JWA `none` algorithm was allowed in all flows.
3) `oic.consumer.Consumer.parse authz` returns an unverified IdToken, with verification left to the implementator's discretion.
4) The `iat` claim was not checked for sanity, allowing it to be in the future.
**Recommendations**
For versions prior to 1.2.1, update to version 1.2.1 to resolve the issues.
As a temporary workaround, consider disabling the use of the JWA `none` algorithm in all flows until the update is applied.
Restrict access to the `oic.consumer.Consumer.parse authz` function to minimize the risk of exploitation until the update is applied.
Avoid using the `iat` claim without proper sanity checks until the update is applied.