Vulnerability · Published Sep 24, 2026 · Assigned by GitHub_M
CVE-2026-57178social-auth-core: VK App backend accepts unsigned callback data when auth_key is missing
High 7.4
In plain English
A high-severity improper authentication in social-core from python-social-auth. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 5% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | social-auth-core | no fix listed | DEBIAN-CVE-2026-57178 |
| Debian:13 | social-auth-core | no fix listed | DEBIAN-CVE-2026-57178 |
| Debian:14 | social-auth-core | 5.0.2-1 | DEBIAN-CVE-2026-57178 |
| PyPI | social-auth-core | 5.0.0 | GHSA-3c93-f73f-qc9h |
| PyPI | social-auth-core | 5.0.0 | PYSEC-2026-4165 |
| Ubuntu:22.04:LTS | python3.10 | no fix listed | UBUNTU-CVE-2026-57178 |
| Ubuntu:24.04:LTS | python3.12 | no fix listed | UBUNTU-CVE-2026-57178 |
| Ubuntu:26.04:LTS | python3.14 | no fix listed | UBUNTU-CVE-2026-57178 |
| Ubuntu:26.10 | python3.14 | no fix listed | UBUNTU-CVE-2026-57178 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| python-social-auth | social-core | < 5.0.0 |
Weakness: CWE-287, CWE-347 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N