CVE-2026-21433
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 · uneditedEmlog is an open source website building system. Versions up to and including 2.5.19 are vulnerable to server-side Out-of-Band (OOB) requests / SSRF via uploaded SVG files. An attacker can upload a crafted SVG to http[:]//emblog/admin/media[.]php which contains external resource references. When the server processes/renders the SVG (thumbnailing, preview, or sanitization), it issues an HTTP request to the attacker-controlled host. Impact: server-side SSRF/OOB leading to internal network probing and potential metadata/credential exposure. As of time of publication, no known patched versions are available.
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 analysisThe server can be induced to make requests to a URL an attacker controls, turning it into a proxy into internal networks and cloud metadata services. It's especially dangerous behind a trusted network boundary. The fix is strict allow-listing of destinations and blocking access to internal address ranges.
General guidance for the server-side request forgery (ssrf) class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
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<= 2.5.19CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
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.
dbcve · scoped- Disable SVG file uploads in Emlog by modifying the media.php upload restrictions to reject .svg file extensions
- If SVG uploads are business-required, implement server-side validation that disables external entity processing and removes or blocks external resource references (xlink:href, href attributes) in SVG files before storage
- Configure a Web Application Firewall (WAF) to inspect uploaded SVG files for suspicious URL patterns and block requests to internal network addresses
- Restrict access to /admin/media.php to trusted IP addresses or require strong authentication
- Implement Content-Security-Policy headers to restrict the server's ability to make outbound HTTP requests
- Monitor server logs for unusual outbound HTTP requests originating from application processes
Generated from the published advisory — verify against the referenced sources before acting.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-21433 — 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-2026-21433 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