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MEDIUM severity

CVE-2021-21043 — acs-aem-commons

MEDIUMFix: Adobe-Consulting-Services/acs-aem-commons@14d769c

CVE-2021-21043 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in com.adobe.acs:acs-aem-commons. A fix is available for com.adobe.acs:acs-aem-commons — see the affected versions and patch details below.

Reflected Cross-site Scripting (XSS) in ACS Commons

Also known asCVE-2021-21028GHSA-7r83-w6r8-fh6wGHSA-f92j-qf46-p6vm
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 1, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
3.4%probability of exploitation in next 30 days
Lower Risk+0.04%
Lower risk than most CVEs89th percentile — riskier than 89% of all scored CVEsHighest risk
0.27%1.54%2.82%4.10%1.0%3.4%May 26Aug 26Nov 26

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
☕com.adobe.acs:acs-aem-commons

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

Description

ACS Commons version 4.9.2 (and earlier) suffers from a Reflected Cross-site Scripting (XSS) vulnerability in version-compare and page-compare due to invalid JCR characters that are not handled correctly. An attacker could potentially exploit this vulnerability to inject malicious JavaScript content into vulnerable form fields and execute it within the context of the victim's browser. Exploitation of this issue requires user interaction in order to be successful.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
☕Mavencom.adobe.acs:acs-aem-commonsall versions4.10.0com.adobe.acs:acs-aem-commons:4.10.0

Affected Products

1 product · 1 configurations
Application
adobe consulting services commonsadobe
≤ 4.9.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update com.adobe.acs:acs-aem-commons to 4.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21043 is resolved across your whole dependency graph.

  3. 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

ACS Commons version 4.9.2 (and earlier) suffers from a Reflected Cross-site Scripting (XSS) vulnerability in version-compare and page-compare due to invalid JCR characters that are not handled correctly. An attacker could potentially exploit this vulnerability to inject malicious JavaScript content into vulnerable form fields and execute it within the context of the victim's browser. Exploitation of this issue requires user interaction in order to be successful.
O3 Security · Impact-Aware SCA

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CVE-2021-21043: acs-aem-commons XSS — Fixed in 4.10.0