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MEDIUM severity

CVE-2021-21028 — acs-aem-commons

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

CVE-2021-21028 is a medium-severity (CVSS 6.1) Use After Free 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 asGHSA-7r83-w6r8-fh6wGHSA-f92j-qf46-p6vm
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 4, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
4.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs91th percentile — riskier than 91% of all scored CVEsHighest risk
0.00%9.56%19.1%28.7%23.0%4.1%May 26Sep 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

4 products · 6 configurations
Application
acrobatadobe
≥ 20.0 && ≤ 20.001.30018
range
Application
acrobat dcadobe
≤ 20.013.20074
range
Application
acrobat readeradobe
≥ 20.0 && ≤ 20.001.300183
range
Application
acrobat reader dcadobe
≤ 20.013.20074
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-2021-21028 is resolved across your whole dependency graph.

  3. Workarounds

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

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-2021-21028: acs-aem-commons XSS — Fixed in 4.10.0