CVE-2021-29106
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 · uneditedA reflected Cross Site Scripting (XSS) vulnerability in Esri ArcGIS Server version 10.8.1 and below may allow a remote attacker able to convince a user to click on a crafted link which could potentially execute arbitrary JavaScript code in the user’s browser.
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 confidenceEsri ArcGIS Server versions 10.8.1 and below contain a reflected XSS vulnerability where malicious JavaScript can be injected via crafted URLs. The attack requires social engineering to trick users into clicking the malicious link, and successful exploitation allows arbitrary JavaScript execution in the victim's browser context.
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< 10.9.0CVSS 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 ArcGIS Server version via REST endpointAccess the ArcGIS Server REST services info endpoint: https://<server>/arcgis/rest/info?f=json and locate the 'server' > 'version' field in the JSON response. Alternatively, log in to the ArcGIS Server Administrator Directory at https://<server>/arcgis/admin and check the version displayed on the login or system info page.Affected if The reported version is below 10.9.0 (for example, 10.8.1, 10.8.0, 10.7.1, etc.)
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Confirm ArcGIS Server is accessible over HTTP/HTTPSVerify that the ArcGIS Server web endpoints are reachable. Try accessing the REST services directory at https://<server>/arcgis/rest/ or the admin directory at https://<server>/arcgis/admin/Affected if The server is accessible and responding, meaning users could potentially be targeted with malicious crafted URLs
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Check if the server handles URL parameters without sanitizationReview ArcGIS Server logs or perform a controlled test by submitting a benign test parameter (such as ?test=<script>alert(1)</script>) to a known REST endpoint like /arcgis/rest/services and observe whether the payload is reflected unescaped in the response. Only perform this in a non-production or test environment.Affected if The URL parameter value is reflected directly in the response without HTML encoding, indicating the XSS vulnerability is present
You are affected if your ArcGIS Server version is below 10.9.0 and the server is accessible to users who could click crafted malicious links.
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 data10.9.0
Upgrade ArcGIS Server to a version above 10.8.1, or apply vendor-supplied patches. Until patched, users should avoid clicking untrusted links.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-29106 — 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-2021-29106 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
- No spam, self-promotion, credentials, or personal data