How severe is CVE-2021-42112?

CVE-2021-42112 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-42112?

CVE-2021-42112 affects the following packages: limesurvey/limesurvey (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2021-42112?

Update limesurvey/limesurvey to 3.27.19 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-42112 is resolved across your whole dependency graph.

How do I detect CVE-2021-42112 in my Packagist dependencies?

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

How do I mitigate CVE-2021-42112 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-2021-42112 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-42112, 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-2021-42112?

CVE-2021-42112 has an EPSS (Exploit Prediction Scoring System) score of 1.5%, placing it in the 75th 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-2021-42112?

CVE-2021-42112 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-2021-42112 published, and has it been updated?

CVE-2021-42112 was published on October 8, 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

MEDIUM severity

CVE-2021-42112 — limesurvey

MEDIUMFix: LimeSurvey/LimeSurvey@d56619a

CVE-2021-42112 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in limesurvey/limesurvey. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for limesurvey/limesurvey — see the affected versions and patch details below.

Cross-site Scripting in Limesurvey

Also known asBIT-limesurvey-2021-42112GHSA-h9ph-jcgh-gf69

Published

Oct 8, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs75th percentile — riskier than 75% 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

🐘limesurvey/limesurvey

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

The "File upload question" functionality in LimeSurvey 3.x-LTS through 3.27.18 allows XSS in assets/scripts/modaldialog.js and assets/scripts/uploader.js.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`limesurvey/limesurvey`	all versions	3.27.19`composer require limesurvey/limesurvey:^3.27.19`

Affected Products

1 product · 1 configurations

Application

limesurveylimesurvey

≥ 3.0.0 && ≤ 3.27.18

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.

The "File upload question" functionality in LimeSurvey 3.x-LTS through 3…

on-x.comNVDDec 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for limesurvey/limesurvey, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update limesurvey/limesurvey to 3.27.19 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-42112 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

The "File upload question" functionality in LimeSurvey 3.x-LTS through 3.27.18 allows XSS in assets/scripts/modaldialog.js and assets/scripts/uploader.js.

O3 Security · Impact-Aware SCA

Is CVE-2021-42112 in your dependencies?

Find it across Packagist, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

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

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

LimeSurvey

4.8/10

Code-Review3/10

Maintained10/10

Branch-Protection3/10

Assessed Nov 9, 2026

Timeline

Disclosed

Oct 8, 2021

First exploit

Dec 3, 2021

Last updated

Oct 20, 2026

Identifiers

CVE-2021-42112

GHSA-h9ph-jcgh-gf69

BIT-limesurvey-2021-42112

References

Advisorynvd.nist.gov · CVE 2021 42112 Fixgithub.com · d56619a50cfd191bbffd0adb660638a5e438070d Reportbugs.limesurvey.org · view Webgithub.com Packagegithub.com · LimeSurvey Evidenceon-x.com · on x security advisory limesurvey cve 2021 42112.pdf

Related vulnerabilities

Also affects limesurvey/limesurvey

This CVE is medium severity; 7 of 7 other CVEs affecting limesurvey/limesurvey are rated as high or higher (top: high).

CVE-2026-50635CVE-2026-50636CVE-2025-56421CVE-2024-28710CVE-2024-28709CVE-2019-16172CVE-2019-16173

Same weakness: CWE-79

This CVE is medium severity, in line with the other 1 CVE with CWE-79.

CVE-2026-126075Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026