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CVE-2026-33525

21
FAUCET Score

CVE-2026-33525 identifies a Cross-site Scripting (XSS) vulnerability in Authelia version 4.39.15, stemming from insufficient neutralization of the `language` cookie value on the login page. This is a low-severity issue (CVSS 0.5) with high attack complexity, as exploitation requires an attacker on an adjacent network and specific, unsafe modifications to the Content Security Policy (CSP) directives. The default CSP configuration completely prevents exploitation, meaning the overwhelming majority of installations are unaffected and impact is minimal. Currently, there is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
4.39.15CPE matchmatch criteria
cpe:2.3:a:authelia:authelia:4.39.15:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 4.0

0.5LOW

CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
ADJACENT
Attack Complexity
HIGH
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
PASSIVE
VS Confidentiality
LOW
VS Integrity
LOW
VS Availability
NONE
SS Confidentiality
LOW
SS Integrity
LOW
SS Availability
NONE
Exploit Maturity
UNREPORTED
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.23%
Probability of exploitation in next 30 days
EPSS Percentile
13.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0023 is in the 14th 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

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)

gopatch availablevia ghsa
Product: github.com/authelia/authelia/v4Fixed in: 4.39.16
github_advisoryworkaround availablevia nvd_reference
View patch

Vendor Advisories (1)

goGHSA-gmfg-3v4q-9qr4low

Authelia: Improper Neutralization of Input During Web Page Generation Leads to Potential Cross-site Scripting

Mar 24, 2026

References

github.com / authelia/authelia/security/advisories/GHSA-gmfg-3v4q-9qr4
ExploitMitigationVendor Advisory