Joomla\!Application · Joomla
CVE-2021-26034
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 Joomla! 3.0.0 through 3.9.26. A missing token check causes a CSRF vulnerability in data download endpoints in com_banners and com_sysinfo.
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 confidenceA CSRF vulnerability in Joomla! versions 3.0.0-3.9.26 allows attackers to exploit missing anti-token validation on data download endpoints in the com_banners and com_sysinfo components. An authenticated administrator could be tricked into unknowingly triggering data downloads via maliciously crafted links or forms.
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
Joomla\!Application
>= 3.0.0, <= 3.9.26CVSS 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
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/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 Joomla versionNavigate to Help > About Joomla in the admin dashboard, or check the /libraries/cms/version.php file for the $RELEASE variable valueAffected if The version falls within 3.0.0 through 3.9.26 inclusive
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Check if com_banners component is enabledLog into Joomla admin, go to Components > Banners, or inspect the #__extensions database table for com_banners with enabled=1Affected if The banners component is installed and enabled on the site
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Check if com_sysinfo component is enabledLog into Joomla admin, go to Components > System Information, or inspect the #__extensions database table for com_sysinfo with enabled=1Affected if The system information component is installed and enabled on the site
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Inspect com_banners download endpoint for CSRF token checkExamine the controller file in /components/com_banners/controllers/ for the download action and verify that JSession::checkToken() or $this->checkToken() is called at the method entryAffected if The download endpoint lacks token validation and the component is enabled
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Inspect com_sysinfo download endpoint for CSRF token checkExamine the controller file in /components/com_sysinfo/controllers/ for download actions and verify that JSession::checkToken() or $this->checkToken() is called at the method entryAffected if The download endpoint lacks token validation and the component is enabled
You are affected if your Joomla version is between 3.0.0 and 3.9.26 and either the com_banners or com_sysinfo component is enabled and the respective download endpoints lack CSRF token validation.
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 CSRF token validation (JSession::checkToken) on the affected download endpoints in com_banners and com_sysinfo, or upgrade to Joomla 3.9.27 or later which contains the patch.
Fix this in Joomla\!
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 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 $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-26034 — 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-2021-26034 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