CVE-2021-3983Network attack vector

Stored script execution via unescaped entity names

Published Dec 1, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in Kimai before 1.16.3 allows remote authenticated users to execute JavaScript in recent-activity views. KimaiRecentActivities inserts customer, project, and activity names into an HTML label without escaping ampersands or angle brackets. An account able to create or rename those entities can store a payload that executes when the affected recent-activity list is rendered in a browser.

CVSS severity6.1
Medium
EPSS probability0.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Kimai before 1.16.3 allows remote authenticated users to execute JavaScript in recent-activity views. KimaiRecentActivities inserts customer, project, and activity names into an HTML label without escaping ampersands or angle brackets. An account able to create or rename those entities can store a payload that executes when the affected recent-activity list is rendered in a browser.

The record

CVE
CVE-2021-3983
Published
Dec 1, 2021
Updated
Aug 3, 2024
Vendor
Kevin Papst
Product
Kimai
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=unspecified <1.16.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Kevin Papst · Kimaiversion=unspecified <1.16.3

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
6.3huntr.devCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

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 exploitUnconfirmed

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

No public exploit references are available in this record.

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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