CVE-2021-3985Network attack vector

Stored cross-site scripting via unsafe Markdown links

Published Dec 1, 2021 · Updated Aug 3, 2024

Cross-site scripting in Kimai before 1.16.3 allows remote authenticated users to execute script via stored Markdown content. Kimai's Markdown helper disabled safe mode and rendered attacker-controlled links, including javascript URLs, in comments and timesheet content. A logged-in user must submit content that another user views; successful exploitation executes script in that viewer's session and can alter displayed data or perform permitted actions.

CVSS severity8.0
High
EPSS probability1.22%
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 Kimai before 1.16.3 allows remote authenticated users to execute script via stored Markdown content. Kimai's Markdown helper disabled safe mode and rendered attacker-controlled links, including javascript URLs, in comments and timesheet content. A logged-in user must submit content that another user views; successful exploitation executes script in that viewer's session and can alter displayed data or perform permitted actions.

The record

CVE
CVE-2021-3985
Published
Dec 1, 2021
Updated
Aug 3, 2024
Vendor
Kevin Papst
Product
Kimai
Classifications
CWE-79, T1189
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

6.0NVDAV:N/AC:M/Au:S/C:P/I:P/A:P
9.0NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
8.0huntr.devCVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 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')
T1189Drive-by Compromise

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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