40 lines
1.7 KiB
Markdown
40 lines
1.7 KiB
Markdown
# CVE-2024-21637
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_Reported by [@lauritzh](https://github.com/lauritzh)_
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## XSS in Authentik via JavaScript-URI as Redirect URI and form_post Response Mode
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### Summary
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Given an OAuth2 provider configured with allowed redirect URIs set to `*` or `.*`, an attacker can send an OAuth Authorization request using `response_mode=form_post` and setting `redirect_uri` to a malicious URI, to capture authentik's session token.
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### Patches
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authentik 2023.8.6 and 2023.10.6 fix this issue.
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### Impact
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The impact depends on the attack scenario. In the following I will describe the two scenario that were identified for Authentik.
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#### Redirect URI Misconfiguration
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While advising that this may cause security issues, Authentik generally allows wildcards as Redirect URI. Therefore, using a wildcard-only effectively allowing arbitrary URLS is possible misconfiguration that may be present in real-world instances.
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In such cases, unauthenticated and unprivileged attackers can perform the above described actions.
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### User with (only) App Administration Permissions
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A more likely scenario is an administrative user (e.g. a normal developer) having only permissions to manage applications.
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This relatively user could use the described attacks to perform a privilege escalation.
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### Workaround
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It is recommended to upgrade to the patched version of authentik. If not possible, ensure that OAuth2 providers do not use a wildcard (`*` or `.*`) value as allowed redirect URI setting. (This is _not_ exploitable if part of the redirect URI has a wildcard, for example `https://foo-.*\.bar\.com`)
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### For more information
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If you have any questions or comments about this advisory:
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- Email us at [security@goauthentik.io](mailto:security@goauthentik.io)
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