CVE-2026-33436
Published: 17 April 2026
Summary
CVE-2026-33436 is a low-severity Improper Input Validation (CWE-20) vulnerability in Stirlingpdf Stirling Pdf. Its CVSS base score is 3.1 (Low).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 31.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-23513
Vulnerability details
Stirling-PDF is a locally hosted web application that facilitates various operations on PDF files. In versions prior to 2.0.0, file upload endpoints render user-supplied filenames directly into HTML using unsafe methods like innerHTML without sanitization. An attacker can craft a…
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file with a malicious filename containing JavaScript that executes in the uploading user's browser context, resulting in reflected XSS. The issue affects numerous upload endpoints across the application. The issue has been fixed in version 2.0.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Reflected XSS via unsanitized filename in web app upload endpoints directly enables client-side JS execution (T1059.007) and exploitation of the public/local web application (T1190).
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.
Directly implements checks on information inputs to reject invalid data before processing.
Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.
Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.
Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.
Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.
Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.