Account takeover via inline uploaded HTML
Published May 26, 2026 · Updated May 26, 2026
Stored XSS in Twenty 1.18.0 and earlier allows remote authenticated users to hijack accounts through victim-opened uploaded HTML. The file controllers pipe arbitrary upload streams into responses without Content-Type, Content-Disposition, or nosniff headers, so browsers render HTML in the CRM origin. A default Member can upload the payload, but a victim must open its file URL before the script gains the victim's session authority and CRM data access.
Summary
What happened
Stored XSS in Twenty 1.18.0 and earlier allows remote authenticated users to hijack accounts through victim-opened uploaded HTML. The file controllers pipe arbitrary upload streams into responses without Content-Type, Content-Disposition, or nosniff headers, so browsers render HTML in the CRM origin. A default Member can upload the payload, but a victim must open its file URL before the script gains the victim's session authority and CRM data access.
The record
- CVE
- CVE-2026-44729
- Published
- May 26, 2026
- Updated
- May 26, 2026
- Vendor
- Twenty
- Product
- Twenty
- Classifications
- CWE-79, T1539, T1204.001
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- May 26, 2026CVE publishedPublication date reported by the CVE source.
- May 26, 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=<= 1.18.0
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
- GHSA-f5h2-3qw5-3qp7 authenticated reproduction scriptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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