GHSA-3C93-F73F-QC9H
Vulnerability from github – Published: 2026-09-24 19:57 – Updated: 2026-09-24 19:57Impact
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.
Patches
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:
- https://github.com/python-social-auth/social-core/pull/1811
Workarounds
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.
Credits
Reported by @lalalala5678 through GitHub private vulnerability reporting.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "social-auth-core"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "5.0.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-57178"
],
"database_specific": {
"cwe_ids": [
"CWE-287",
"CWE-347"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-24T19:57:22Z",
"nvd_published_at": "2026-09-24T18:17:14Z",
"severity": "HIGH"
},
"details": "### Impact\n\nThe `vk-app` backend accepted VK application callback data without verifying the callback signature when the `auth_key` parameter was omitted.\n\nApplications 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.\n\nThe issue affects only applications using the `vk-app` backend.\n\n### Patches\n\nThe issue has been fixed by requiring `auth_key` to be present and valid before callback data is trusted.\n\nUsers should upgrade to a patched version.\n\nFix:\n\n* https://github.com/python-social-auth/social-core/pull/1811\n\n### Workarounds\n\nApplications that cannot upgrade immediately should disable the `vk-app` backend by removing `social_core.backends.vk.VKAppOAuth2` from `SOCIAL_AUTH_AUTHENTICATION_BACKENDS`.\n\nThere is no complete workaround while continuing to use the vulnerable backend.\n\n### Credits\n\nReported by @lalalala5678 through GitHub private vulnerability reporting.",
"id": "GHSA-3c93-f73f-qc9h",
"modified": "2026-09-24T19:57:22Z",
"published": "2026-09-24T19:57:22Z",
"references": [
{
"type": "WEB",
"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"
},
{
"type": "WEB",
"url": "https://github.com/python-social-auth/social-core/pull/1811"
},
{
"type": "WEB",
"url": "https://github.com/python-social-auth/social-core/commit/1bfacdd0379e5eb46e169a99ab648b835e9bb6a2"
},
{
"type": "PACKAGE",
"url": "https://github.com/python-social-auth/social-core"
},
{
"type": "WEB",
"url": "https://github.com/python-social-auth/social-core/releases/tag/5.0.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "social-auth-core: VK App backend accepts unsigned callback data when auth_key is missing"
}
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