Auth bypass in Python-Social-Auth Social-Core

CVE-2026-57175

Python Social Auth is a social authentication/registration mechanism. Prior to version 5.0.0, the SAML backend accepted SAML responses on the Assertion Consumer Service endpoint without verifying that they matched a previously issued `AuthnRequest`. Applications using SAML account association could allow an attacker with a valid account on a trusted IdP to link the attacker's SAML identity to a logged-in victim's local account. The attacker could then authenticate through SAML and gain access to the victim's account. The issue affects applications using the SAML backend together with authenticated account association. The issue has been fixed in version 5.0.0 by validating SAML responses against stored `AuthnRequest` IDs.

Vulnerability class: Broken Authentication

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 13.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-57175: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-57175?
CVE-2026-57175 is a medium-severity vulnerability in Python-Social-Auth Social-Core, classified under Improper Authentication. CVSS score: 6.4/10. Published 2026-09-24.
How severe is CVE-2026-57175?
Medium severity. CVSS v3 base score is 6.4 out of 10.