{"id":"CVE-2026-57178","summary":"social-auth-core: VK App backend accepts unsigned callback data when auth_key is missing","details":"Python Social Auth is a social authentication/registration mechanism. Prior to version 5.0.0, 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 in version 5.0.0 by requiring `auth_key` to be present and valid before callback data is trusted.","aliases":["GHSA-3c93-f73f-qc9h"],"modified":"2026-09-25T03:48:33.317127070Z","published":"2026-09-24T17:25:47.225Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-287","CWE-347"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/57xxx/CVE-2026-57178.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/57xxx/CVE-2026-57178.json"},{"type":"ADVISORY","url":"https://github.com/python-social-auth/social-core/security/advisories/GHSA-3c93-f73f-qc9h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-57178"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/python-social-auth/social-core","events":[{"introduced":"0"},{"fixed":"29dffe68c7c23f3d5cb5e051e7cb40447ffb55d5"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"fixed":"5.0.0"}]}}],"versions":["4.9.1","4.9.0","4.8.7","4.8.6","4.8.5","4.8.4","4.8.3","4.8.2","4.8.1","4.8.0","4.7.0","4.6.1","4.6.0","4.5.6","4.5.5","4.5.4","4.5.3","4.5.2","4.5.1","4.5.0","4.4.2","4.4.1","4.4.0","4.3.0","4.2.0","4.1.0","4.0.3","4.0.2","4.0.1","4.0.0","3.4.0","3.3.3","3.1.0","3.3.2","3.3.1","3.3.0","3.2.0","3.0.0","2.0.0","1.7.0","1.6.0","1.5.0","1.4.0","1.3.0","1.2.0","1.1.0","1.0.1","0.2.1","0.2.0","0.1.0","0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-57178.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"}]}