CVE-2026-70556

Description

Hubzilla 11.2.1 contains a cross-site request forgery vulnerability in the OAuth2 /authorize endpoint handled by Zotlabs\Module\Authorize::post() that allows unauthenticated attackers to register arbitrary OAuth2 applications under an authenticated user's account by submitting a cross-origin POST request without CSRF token or Origin/Referer validation. Attackers can craft a malicious HTML form that autosubmits attacker-chosen OAuth2 parameters including client_id, client_secret, redirect_uri, and scope to silently register a persistent OAuth2 application, enabling interception of future OAuth2 authorization codes when the victim later authenticates against the attacker-controlled client.

References

• https://framagit.org/hubzilla/core
• https://framagit.org/hubzilla/core/-/blob/dev/Zotlabs/Module/Authorize.php?ref_type=heads#L49
• https://hub.volse.no/cloud/harald/Skjermopptak_20260616_095037.webm
• https://www.vulncheck.com/advisories/hubzilla-csrf-via-oauth2-authorize-endpoint-app-registration
• https://hub.volse.no/cloud/harald/Skjermopptak_20260616_095037.webm