Cyber Resilience

CVE-2026-39970

High

Published: 22 May 2026

Published
22 May 2026
Modified
22 May 2026
KEV Added
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Patch
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CVSS Score v4 8.5 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0028 19.4th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2026-39970 is a high-severity Cross-site Scripting (CWE-79) vulnerability. Its CVSS base score is 8.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 19.4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability details

TypeBot is a chatbot builder tool. Versions 3.15.2 and prior contain a critical stored XSS vulnerability in the app.typebot.io profile picture upload form. The application fails to sanitize or restrict SVG/XML-based uploads and directly renders them when accessed through the…

more

domain. By uploading a crafted malicious SVG file containing embedded JavaScript, an attacker will execute arbitrary JavaScript code. This vulnerability directly enables stored XSS exploitation because the payload is persistently stored on your infrastructure (app.typebot.io) and accessible from a public-facing, permanent link. Stored XSS via malicious SVG uploads to app.typebot.io allows attackers to execute arbitrary JavaScript in victims' browsers, enabling session/token theft, account takeover, and exfiltration of sensitive user data. This issue has been fixed in version 3.16.0.

CWE(s)
CWE-79

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1059.007 JavaScript Execution
Adversaries may abuse various implementations of JavaScript for execution.
attack.mitre.org →
Why these techniques?

Stored XSS via unsanitized SVG upload on public-facing app (app.typebot.io) directly enables T1190 exploitation and arbitrary JS execution (T1059.007) in victim browsers.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

SI-10 Information Input Validation
addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

SI-15 Information Output Filtering
addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

References