CVE-2021-3026
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 · uneditedInvision Community IPS Community Suite before 4.5.4.2 allows XSS during the quoting of a post or comment.
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 confidenceInvision Community IPS Community Suite before version 4.5.4.2 contains a cross-site scripting (XSS) vulnerability where malicious scripts can be injected through the quoting mechanism of posts or comments. User-supplied content within quotes is not properly sanitized, allowing attackers to execute arbitrary JavaScript in the browsers of other users who view the quoted content.
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< 4.5.4.2CVSS 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
- 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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Locate the installed version numberAccess the Invision Community admin panel and navigate to System > Overview, or check the version info in the file /docs/changelog.txt or the application config file in the root directory.Affected if The displayed version is any version number less than 4.5.4.2 (for example, 4.5.4.1, 4.5.3, 4.4.x, etc.)
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Verify the quoting feature is enabledIn the admin panel, go to Posts and Comments settings and confirm that the quoting/reply-to-quote functionality is enabled for forum posts or content comments.Affected if The quote reply feature is active and users can create or view quoted content in posts or comments
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Inspect the quote content handlingCreate a test post with a quoted reply containing script tags in the quote attribution or content, then view the rendered page source to see if the script tags are stripped, encoded, or left intact.Affected if The script tags or HTML markup within quoted content are rendered as-is in the browser without sanitization or encoding
A user is affected if their Invision Community installation shows a version lower than 4.5.4.2 and the quoting feature is enabled, allowing unsanitized script execution when viewing quoted content.
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 data4.5.4.2
Upgrade Invision Community IPS Community Suite to version 4.5.4.2 or later to obtain the patch for this XSS vulnerability.
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3026 — 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-2021-3026 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