CVE-2026-40479Public exploitNetwork attack vector

Stored XSS via incomplete attribute escaping

Published Apr 17, 2026 · Updated Apr 17, 2026

Stored XSS in Kimai 1.16.3 through 2.52.0 allows remote authenticated users to execute JavaScript in an administrator's browser. The escapeForHtml() function in KimaiEscape.js omits single- and double-quote escaping before an alias enters the team-member title attribute through innerHTML. ROLE_USER access is sufficient to store the alias, but an administrator must view the team form; execution then occurs in that privileged browser session.

CVSS severity5.4
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Kimai 1.16.3 through 2.52.0 allows remote authenticated users to execute JavaScript in an administrator's browser. The escapeForHtml() function in KimaiEscape.js omits single- and double-quote escaping before an alias enters the team-member title attribute through innerHTML. ROLE_USER access is sufficient to store the alias, but an administrator must view the team form; execution then occurs in that privileged browser session.

The record

CVE
CVE-2026-40479
Published
Apr 17, 2026
Updated
Apr 17, 2026
Vendor
Kimai
Product
Kimai
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 17, 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=>= 1.16.3, < 2.53.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Kimai · Kimaiversion=>= 1.16.3, < 2.53.0

Published CVSS scores

5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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