CVE-2021-31858
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 · uneditedDotNetNuke (DNN) 9.9.1 CMS is vulnerable to a Stored Cross-Site Scripting vulnerability in the user profile biography section which allows remote authenticated users to inject arbitrary code via a crafted payload.
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 confidenceDotNetNuke (DNN) version 9.9.1 contains a stored Cross-Site Scripting vulnerability in the user profile biography field. Authenticated users can inject malicious JavaScript or HTML payloads into the biography section, which executes when other users view the infected profile.
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<= 9.10.2CVSS 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
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/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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Determine installed DNN versionCheck the version through the DNN admin interface (Admin > About) or inspect the bin/AssemblyInfo.cs file, or look for the version in the web.config file under the assembly binding sectionAffected if Version is 9.10.2 or lower (any version up to and including 9.10.2)
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Confirm user profile functionality is enabledNavigate to Admin > Site Settings or Admin > User Account Settings and verify that user profiles are not disabled. Default installations allow users to edit their profiles.Affected if User profile feature is enabled (this is the default and typical configuration)
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Verify if the biography field existsLog in as an authenticated user, go to the user profile editing page (typically /profile or My Profile) and confirm the biography/bio field is present and editableAffected if The biography field is present and accessible to authenticated users
If your DNN installation version is 9.10.2 or lower and user profiles with biography fields are enabled, you are affected by this stored XSS vulnerability.
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.
dbcve · scopedImplement input validation and output encoding/sanitization on the user profile biography field. Apply context-appropriate escaping when displaying user-supplied content in profiles.
DNN 9.11.0 or later (minimum 9.10.3 which contains the security fix)
- 1. Back up your current DNN database and website files
- 2. Download the latest DNN 9.x platform from the official DNN website (dnnsoftware.com)
- 3. Review the upgrade instructions in the DNN documentation for your specific version path
- 4. Execute the upgrade installer, ensuring the application pool identity has appropriate permissions
- 5. After upgrade, verify the user profile biography field now properly sanitizes input
- 6. Test that authenticated users can still save profile information without XSS payloads executing
Generated from the published advisory — verify against the referenced sources before acting.
- 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-2021-31858 — 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-2021-31858 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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