CVE-2026-8891
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 · uneditedThe BitForm plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's 'bitform' shortcode in versions up to, and including, 1.1.0. This is due to insufficient input sanitization and output escaping on user-supplied shortcode attributes ('width' and 'height') in the Shortcode::shortcode() function, which are interpolated directly into the 'style' attribute of an <iframe> element. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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 confidenceThe BitForm WordPress plugin fails to sanitize and escape the 'width' and 'height' attributes in its shortcode handler, allowing authenticated users with contributor-level access to inject arbitrary JavaScript into pages. The unescaped values are directly placed into an iframe's style attribute, causing the malicious script to execute when visitors access the affected page.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- None
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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 BitForm plugin installationCheck the WordPress plugins directory or use wp plugin list to see if BitForm is installed and activeAffected if BitForm plugin is installed and active in WordPress
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Determine installed BitForm versionCheck the plugin version via WordPress admin plugins page, wp plugin list, or read the plugin header in bitform.phpAffected if Version is 1.1.0 or earlier (the vulnerable version range)
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Locate shortcode usage in contentSearch WordPress posts, pages, and custom post types for the BitForm shortcode (typically [bitform]) containing width or height attributesAffected if Shortcode with width or height attributes is present in any published content
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Check for contributor-level usersList WordPress users with contributor role using wp user list --role=contributor or via WordPress admin users panelAffected if At least one user with contributor role exists and can edit content
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Inspect shortcode output for unescaped attributesView the source HTML of a page containing the BitForm shortcode and examine the iframe style attribute for width/height valuesAffected if The iframe style attribute contains raw, unescaped values from the shortcode that could contain JavaScript
User is affected if BitForm plugin version 1.1.0 or earlier is installed, the shortcode with width/height attributes is in use, and the output shows unescaped values in the iframe style attribute.
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 dataUpdate BitForm to a version beyond 1.1.0 that implements proper input sanitization (e.g., using sanitize_css_dimension() or numeric validation) and output escaping (e.g., using esc_attr()) on shortcode attributes before rendering them in the iframe style attribute.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 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 $2,224.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-8891 — 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-2026-8891 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