Stored XSS via unsanitized SVG uploads
Published May 12, 2026 · Updated May 12, 2026
Stored XSS in FluentCMS 1.2.3 allows remote authenticated users to execute JavaScript in visitors' browsers through SVG uploads. FileService.Create() stores uploaded SVG content without removing script elements, event-handler attributes, or dangerous URL schemes, and public file serving lacks restrictive security headers. Administrator access is required to plant the file, and execution occurs only when a user, including an unauthenticated visitor, opens its direct URL.
Summary
What happened
Stored XSS in FluentCMS 1.2.3 allows remote authenticated users to execute JavaScript in visitors' browsers through SVG uploads. FileService.Create() stores uploaded SVG content without removing script elements, event-handler attributes, or dangerous URL schemes, and public file serving lacks restrictive security headers. Administrator access is required to plant the file, and execution occurs only when a user, including an unauthenticated visitor, opens its direct URL.
The record
- CVE
- CVE-2025-70842
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-79, T1204.001
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream SVG upload proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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