How severe is CVE-2021-3985?

CVE-2021-3985 has a CVSS score of 9/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-3985?

CVE-2021-3985 affects the following packages: kevinpapst/kimai2 (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-3985?

Update kevinpapst/kimai2 to 1.16.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3985 is resolved across your whole dependency graph.

How do I detect CVE-2021-3985 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kevinpapst/kimai2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-3985 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Is CVE-2021-3985 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-3985, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-3985?

CVE-2021-3985 has an EPSS (Exploit Prediction Scoring System) score of 1.3%, placing it in the 70th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-3985?

CVE-2021-3985 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2021-3985 published, and has it been updated?

CVE-2021-3985 was published on December 1, 2021 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘

🐘 Packagist

Not in CISA KEV

CRITICAL severity

CVE-2021-3985 — kimai2

CRITICALFix: kevinpapst/kimai2@76e0944

CVE-2021-3985 is a critical-severity (CVSS 9) Cross-site Scripting (XSS) vulnerability in kevinpapst/kimai2. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for kevinpapst/kimai2 — see the affected versions and patch details below.

kimai2 is vulnerable to Cross-site Scripting

Also known asGHSA-x68c-4gmm-5g43

Published

Dec 1, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs70th percentile — riskier than 70% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐘kevinpapst/kimai2

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

kimai2 is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`kevinpapst/kimai2`	all versions	1.16.3`composer require kevinpapst/kimai2:^1.16.3`

Affected Products

1 product · 1 configurations

Application

kimai2kimai

< 1.16.3

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

kimai2 is vulnerable to Improper Neutralization of Input During Web Page…

huntr.devNVDDec 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for kevinpapst/kimai2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update kevinpapst/kimai2 to 1.16.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3985 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

kimai2 is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

O3 Security · Impact-Aware SCA

Is CVE-2021-3985 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

9/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No Nuclei template or Metasploit module yet. 1 public proof-of-concept reference is listed on this page.

OpenSSF Scorecard

Package health score

kimai2

5.9/10

Code-Review1/10

Maintained10/10

Branch-ProtectionN/A

Assessed Oct 26, 2026

Timeline

Disclosed

Dec 1, 2021

First exploit

Dec 2, 2021

1 day after disclosure — rapid exploitation

Last updated

Oct 20, 2026

Identifiers

CVE-2021-3985

GHSA-x68c-4gmm-5g43

References

Advisorynvd.nist.gov · CVE 2021 3985 Fixgithub.com · 76e09447c85e762882126b49626a4fe4d93fe8b5 Fixhuntr.dev · 89d6c3de efbd 4354 8cc8 46e999e4c5a4 Webgithub.com · 1.16.3 Packagegithub.com · kimai2

Related vulnerabilities

This CVE is critical severity — higher than any of the other 8 CVEs affecting kevinpapst/kimai2 (highest there: high).

CVE-2019-15481CVE-2021-43515CVE-2021-4033CVE-2021-3983CVE-2021-3992CVE-2021-3957CVE-2021-3976CVE-2021-3963

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026

CVE-2021-3985 — kimai2

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2021-3985 in your dependencies?