CVE-2026-57175: Auth Bypass (CVSS 6.4)

Description

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.

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CVSS v3.1 Score

6.4

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.12%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-287 Improper Authentication

References

Other References

https://github.com/python-social-auth/social-core/security/advisories/GHSA-vq6g-g6c7-5f2j

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 6.4 (MEDIUM).

How severe is CVE-2026-57175? +

CVE-2026-57175 has a CVSS v3.1 score of 6.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-57175? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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