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CVE-2021-29456

18
FAUCET Score

CVE-2021-29456 is an open redirect vulnerability affecting Authelia versions 4.27.4 and earlier, allowing an attacker to redirect users to arbitrary, potentially malicious, domains via a crafted HTTP query parameter. Rated Medium (CVSS 5.4), this vulnerability requires user interaction and low privileges, with a potential impact on confidentiality and integrity due to phishing risks, though it does not directly compromise the Authelia application itself. There is no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.28.0CPE matchmatch criteria
cpe:2.3:a:authelia:authelia:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.7MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.1
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.51%
Probability of exploitation in next 30 days
EPSS Percentile
40.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0051 is in the 62nd percentile among its peer group of 15,225 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 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 0.0 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/authelia/authelia/v4Fixed in: 4.28.0

Vendor Advisories (1)

goGHSA-36f2-fcrx-fp4jmedium

Authelia allows open redirects on the logout endpoint

Mar 16, 2023

References

github.com / authelia/authelia/security/advisories/GHSA-36f2-fcrx-fp4j
PatchThird Party Advisory