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A GitHub-reviewed security advisory, not necessarily under active exploitation the way our CISA KEV advisories are, but a real, disclosed vulnerability in an open-source dependency.
Affected packages
Vulnerable: < 5.0.0
Patched in 5.0.0
Details
The vk-app backend accepted VK application callback data without verifying the callback signature when the auth_key parameter was omitted.
Applications using this backend could treat unsigned attacker-controlled data as a verified VK identity. An attacker could choose callback fields such as viewer_id, access_token, api_id, and api_result, potentially allowing authentication as an arbitrary VK user ID.
The issue affects only applications using the vk-app backend.
The issue has been fixed by requiring auth_key to be present and valid before callback data is trusted.
Users should upgrade to a patched version.
Fix:
Applications that cannot upgrade immediately should disable the vk-app backend by removing social_core.backends.vk.VKAppOAuth2 from SOCIAL_AUTH_AUTHENTICATION_BACKENDS.
There is no complete workaround while continuing to use the vulnerable backend.
Reported by @lalalala5678 through GitHub private vulnerability reporting.
EPSS, exploit probability
Low0.16%
estimated chance of real-world exploitation in the next 30 days, higher than 5.2% of every CVE FIRST.org scores
Refreshed 11/9/2026, via FIRST.org's EPSS model, not CVSS, this measures likelihood of exploitation, not how severe it would be.
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A secure code review or supply chain review finds this before an advisory does.