CVE-2026-33525

Login-page script injection via unescaped language cookie

Published Mar 26, 2026 · Updated Mar 26, 2026

Cross-site scripting in Authelia 4.39.15 allows attackers to inject JavaScript into the login page through a crafted language cookie. The login-page HTML template renders the user-controllable language cookie without neutralizing its value. Exploitation requires user interaction, unsafe script-src and connect-src policies, and a related application able to set an Authelia-domain cookie.

CVSS severity2.1
Low
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in Authelia 4.39.15 allows attackers to inject JavaScript into the login page through a crafted language cookie. The login-page HTML template renders the user-controllable language cookie without neutralizing its value. Exploitation requires user interaction, unsafe script-src and connect-src policies, and a related application able to set an Authelia-domain cookie.

The record

CVE
CVE-2026-33525
Published
Mar 26, 2026
Updated
Mar 26, 2026
Vendor
Authelia
Product
Authelia
Classifications
CWE-79
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion== 4.39.15

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Authelia · Autheliaversion== 4.39.15

Published CVSS scores

0.5GitHub, Inc.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
6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
2.1GitHub, Inc.CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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