In OAuth2 Proxy before 5.1.1, there is an open redirect vulnerability. 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. However, by crafting a redirect URL with HTML encoded whitespace characters the validation could be bypassed and allow a redirect to any URL provided. This has been patched in 5.1.1.
This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.1, indicating it can be exploited remotely over the network with relatively low complexity though user interaction is required and does not require pre-existing privileges . The vulnerability impacts limited data confidentiality, limited integrity, and limited availability for affected systems. Impacting 1 product from oauth2_proxy_project organizations running these solutions should prioritize assessment and patching.
Reported in 2020, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2020-05-07T21:15:11.530
2026-06-17T02:48:57.090
Modified
CVSSv3.1: 7.1 (HIGH)
AV:N/AC:M/Au:N/C:P/I:P/A:N
8.6
4.9
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | oauth2_proxy_project | oauth2_proxy | < 5.1.1 | Yes |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For oauth2_proxy_project's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.