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CVE-2021-21291

20
FAUCET Score

CVE-2021-21291 is a medium-severity vulnerability affecting OAuth2 Proxy versions prior to 7.0.0. It allows for an open redirect due to improper validation of whitelisted domains, where a malicious domain ending similarly to an intended domain could be permitted. This vulnerability has a CVSS score of 6.1, indicating a network-based attack requiring user interaction, with potential for low confidentiality and integrity impacts. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 7.0.0CPE matchmatch criteria
cpe:2.3:a:oauth2_proxy_project:oauth2_proxy:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.7MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
1.6
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.35%
Probability of exploitation in next 30 days
EPSS Percentile
68.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0135 is in the 81st percentile among its peer group of 26,221 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
gopatch availablevia ghsa
Product: github.com/oauth2-proxy/oauth2-proxy/v7Fixed in: 7.0.0

Vendor Advisories (1)

goGHSA-4mf2-f3wh-gvf2low

Subdomain checking of whitelisted domains could allow unintended redirects in oauth2-proxy

May 25, 2021

References

github.com / oauth2-proxy/oauth2-proxy/commit/780ae4f3c99b579cb2ea9845121caebb6192f725
PatchThird Party Advisory
github.com / oauth2-proxy/oauth2-proxy/releases/tag/v7.0.0
Release NotesThird Party Advisory
github.com / oauth2-proxy/oauth2-proxy/security/advisories/GHSA-4mf2-f3wh-gvf2
ExploitThird Party Advisory
pkg.go.dev / github.com/oauth2-proxy/oauth2-proxy/v7
ProductThird Party Advisory