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Vulnerability record · CVE-2020-4037 · published 29 June 2020

CVE-2020-4037: Oauth2 proxy project oauth2 proxy open redirect vulnerability

OOauth2 Proxy Project · Oauth2 Proxy

In OAuth2 Proxy from version 5.1.1 and less than version 6.0.0, users can provide a redirect address for the proxy to send the authenticated user to at the end of the authentication flow. This is expected to be the original URL that the user was trying to access. This redirect URL is checked within the proxy and validated before redirecting the user to prevent malicious actors providing redirects to potentially harmful sites. This has been fixed in version 6.0.0.

5.4 CVSS 3.1 Medium EPSS 0.90% · top 42.0% CWE-601 · Open redirect
5.4CVSS 3.1 base score, v2 5.8
0.90%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

In OAuth2 Proxy from version 5.1.1 and less than version 6.0.0, users can provide a redirect address for the proxy to send the authenticated user to at the end of the authentication flow. This is expected to be the original URL that the user was trying to access. This redirect URL is checked within the proxy and validated before redirecting the user to prevent malicious actors providing redirects to potentially harmful sites. This has been fixed in version 6.0.0.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/oauth2-proxy/oauth2-proxy/commit/ee5662e0f5001d76ec76562bb605abbd07c266a2 PatchThird Party Advisory
https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-5m6c-jp6f-2vcv Third Party Advisory
https://github.com/oauth2-proxy/oauth2-proxy/commit/ee5662e0f5001d76ec76562bb605abbd07c266a2 PatchThird Party Advisory
https://github.com/oauth2-proxy/oauth2-proxy/security/advisories/GHSA-5m6c-jp6f-2vcv Third Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2020-4037), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.