CVE-2026-29840
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 · uneditedJiZhiCMS v2.5.6 and before contains a Stored Cross-Site Scripting (XSS) vulnerability in the release function within app/home/c/UserController.php. The application attempts to sanitize input by filtering <script> tags but fails to recursively remove dangerous event handlers in other HTML tags (such as onerror in <img> tags). This allows an authenticated remote attacker to inject arbitrary web script or HTML via the body parameter in a POST request to /user/release.html.
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 confidenceJiZhiCMS v2.5.6 and before has a stored XSS in the release function (UserController.php). The application filters <script> tags but fails to recursively sanitize dangerous event handlers like onerror in other HTML tags (e.g., <img>), allowing authenticated attackers to inject arbitrary JavaScript via the body parameter in POST /user/release.html.
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<= 2.5.6CVSS 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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Identify the installed JiZhiCMS versionCheck the version number in the admin dashboard (typically under System > Site Settings or similar), or examine version files in the application root directory for a version.php or similar file that declares the CMS version.Affected if The installed version is 2.5.6 or any version lower than 2.5.6.
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Verify the release functionality existsConfirm that the /user/release.html endpoint is present and accessible within the application by accessing it via a web browser or checking the application's routing configuration.Affected if The /user/release.html endpoint exists and is reachable.
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Confirm authentication is enabled for the release functionCheck that user authentication is required to access the release function. Review UserController.php to verify that the release action enforces login checks before allowing POST submissions.Affected if The release function accepts authenticated user submissions via POST.
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Examine input sanitization in UserController.phpReview the release function code in UserController.php to determine if sanitization only filters <script> tags without recursively removing event handlers like onerror, onload, or onmouseover from other HTML tags.Affected if The code filters <script> tags but does not recursively sanitize event handler attributes in other HTML tags.
A user is affected if they are running JiZhiCMS version 2.5.6 or lower, the /user/release.html endpoint exists, and the application's input sanitization only removes script tags without handling event handlers in other HTML tags.
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 dataImplement comprehensive input sanitization that removes all HTML tags and event handlers (not just <script> tags), or use a mature HTML sanitization library; additionally apply output encoding when rendering user-submitted content.
- Consultation3.0 h
- Implementation4.0 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 $3,408.
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Free · runs locallyCheck whether your project pulls in CVE-2026-29840 — 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-2026-29840 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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- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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