CVE-2021-21084
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAEM's Cloud Service offering, as well as versions 6.5.7.0 (and below), 6.4.8.3 (and below) and 6.3.3.8 (and below) are affected by a stored Cross-Site Scripting (XSS) vulnerability that could be abused by an attacker to inject malicious scripts into vulnerable form fields. Malicious JavaScript may be executed in a victim’s browser when they browse to the page containing the vulnerable field.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceAdobe Experience Manager suffers from a stored XSS vulnerability allowing attackers to inject malicious JavaScript into form fields. When victims browse pages containing these compromised fields, the injected scripts execute in their browsers, potentially enabling session hijacking or credential theft.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 6.3.3.8>= 6.4.0.0, < 6.4.8.4>= 6.5.0.0, < 6.5.8.0all versionsCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify installed AEM versionNavigate to the AEM Welcome page or check the com.adobe.granite.package info via the OSGi web console at /system/console/bundles, or run: curl -s -u admin:password http://localhost:4502/crx/packmgr/service.jsp?cmd=ls 2>/dev/null | grep versionAffected if Version is <= 6.3.3.8, OR between 6.4.0.0 and 6.4.8.3 inclusive, OR between 6.5.0.0 and 6.5.7.x inclusive, OR running on AEM Cloud Service (any version)
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Locate form-enabled content pagesSearch the CRX/DE repository at /libs or /apps for form components such as granite/form, core/wcm/components/form, or custom form containers. Use CRXDE Lite (accessible at /crx/de) or query via the Query Builder API.Affected if Any custom or OOTB form components that accept user input and render submitted values are present in the content tree
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Inspect form field output encodingExamine the JSP, HTL (Sightly), or Granite UI component files under /apps for the form components in use. Look for presence of encoding utilities such as xss-api, text.encode, or XSSAPI in the rendering logic.Affected if Form fields render user-submitted values without proper context-aware encoding (e.g., no use of XSSAPI or equivalent escaping functions)
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Check for existing malicious scripts in form dataQuery the JCR repository for stored XSS patterns in form submission nodes. Example AEM QueryBuilder URL: /bin/querybuilder.json?type=nt:unstructured&1_property=jcr:content&1_value=%3Cscript%3E. Also inspect form submission nodes under /content/forms/af or custom form containers.Affected if Any stored <script> tags, event handlers (onerror, onload), or JavaScript: URIs are found in form field content nodes
You are affected if your AEM version falls within the vulnerable ranges OR you are on Cloud Service AND your forms lack output encoding, allowing stored XSS payloads to persist and execute when viewed.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor data6.4.8.46.5.8.0
Upgrade AEM to version 6.5.8.0, 6.4.8.4, 6.3.3.9 or later. Additionally, implement output encoding and input validation on all form fields to prevent XSS.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-21084 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-21084 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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