CVE-2021-28968
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 · uneditedAn issue was discovered in PunBB before 1.4.6. An XSS vulnerability in the [email] BBcode tag allows (with authentication) injecting arbitrary JavaScript into any forum message.
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 confidenceAn authenticated Cross-Site Scripting (XSS) vulnerability exists in the [email] BBcode tag parser of PunBB versions prior to 1.4.6. An authenticated attacker can inject arbitrary JavaScript code within forum messages by crafting a malicious [email] BBcode tag, leading to session hijacking or defacement when viewed by other users.
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< 1.4.6CVSS 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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Confirm PunBB installationLook for PunBB forum software in your web root. Check for the presence of directories like /include/, /lang/, /style/ and files like index.php, viewforum.php that are characteristic of a PunBB installation.Affected if PunBB forum software is not present on the server.
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Determine installed PunBB versionLocate the version.php file in the include/ directory, or view the footer of any forum page to display the installed version number. Alternatively, check the config.php file for version information.Affected if You cannot locate a version number or the version displayed is lower than 1.4.6.
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Compare version to affected rangeIf you found a version number, compare it against the vulnerable range: any version prior to 1.4.6 (for example, 1.4.5, 1.4.4, 1.4.0, 1.3.x, etc.).Affected if The installed version is less than 1.4.6.
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Verify user authentication is enabledCheck if user registration is open or if existing user accounts can post to the forum. Review the forum settings in the administration panel under Registration and Users section to confirm authenticated users can submit posts.Affected if User registration is disabled AND no authenticated users exist to post content.
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Confirm BBcode parsing is activeIn the forum administration panel, navigate to Configuration > Features and check if BBcode in posts is enabled. Alternatively, attempt to post a simple [b]test[/b] BBcode tag and verify it renders as bold text when the post is displayed.Affected if BBcode parsing is disabled in forum settings.
Your environment is affected if a PunBB installation with version lower than 1.4.6 is running and the forum allows authenticated users to post with BBcode enabled.
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 data1.4.6
Upgrade PunBB to version 1.4.6 or later to patch the vulnerable BBcode tag parser. Until the upgrade is applied, restrict or carefully review forum posting permissions.
- Consultation2.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-28968 — 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-2021-28968 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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