Stored XSS via unfiltered iframe srcdoc attribute
Published Apr 8, 2026 · Updated Apr 8, 2026
Stored XSS in CI4MS before 0.31.4.0 allows remote authenticated users with settings access to execute JavaScript in visitors' browsers. compInfosPost() preserves iframe tags and removes only on-prefixed handlers, so an entity-encoded srcdoc payload is stored and later rendered without attribute filtering or encoding. An administrator with Settings update permission must save the payload; any visitor to a page containing the Google Maps widget then receives same-origin script execution.
Summary
What happened
Stored XSS in CI4MS before 0.31.4.0 allows remote authenticated users with settings access to execute JavaScript in visitors' browsers. compInfosPost() preserves iframe tags and removes only on-prefixed handlers, so an entity-encoded srcdoc payload is stored and later rendered without attribute filtering or encoding. An administrator with Settings update permission must save the payload; any visitor to a page containing the Google Maps widget then receives same-origin script execution.
The record
- CVE
- CVE-2026-39390
- Published
- Apr 8, 2026
- Updated
- Apr 8, 2026
- Vendor
- Ci4MS
- Product
- CI4MS
- Classifications
- CWE-79, T1059.007
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Apr 8, 2026CVE publishedPublication date reported by the CVE source.
- Apr 8, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.31.4.0
What conditions does exploitation require?
What is affected?
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
- GitHub advisory srcdoc stored-XSS proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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