CVE-2026-33437

Stirling-PDF from 2.13.2 through 3.2.0 contains an incomplete denylist in DatabaseService.validateSqlContent() that allows administrators to bypass H2 import restrictions using CREATE OR REPLACE ALIAS. Authenticated administrators can upload a crafted SQL backup to the import-database endpoint, where RUNSCRIPT defines H2 Java function aliases and restores Java-method execution.

In Stirling-PDF prior to 2.13.2, an authenticated administrator using the default H2 database and security mode can upload a crafted SQL file to POST /api/v1/database/import-database. DatabaseService.validateSqlContent() splits normalized input on semicolons and accepts a statement when it contains any allowed keyword, allowing dangerous H2 functions such as FILE_READ and CSVWRITE, plus CREATE ALIAS, to bypass the insufficient whitelist and execute side effects when RUNSCRIPT processes the file. This permits arbitrary file access. The demonstrated operating-system command execution chain writes attacker-controlled startup files to a user-site location and then triggers an application Python interpreter configured to load those startup files, resulting in command execution as the JVM service account.

In Stirling-PDF prior to 3.0.0, the POST /api/v1/ai/tools/create-pdf-from-html-agent endpoint accepts attacker-controlled htmlContent and passes it to WeasyPrint without CustomHtmlSanitizer, unlike the sanitized /api/v1/convert/html/pdf control path. HTTP and HTTPS resource references can make server-side requests to internal or cloud-metadata destinations, while file references can embed local content readable by the Stirling-PDF process into the generated PDF. The endpoint is reachable without credentials when security.enableLogin is false.

In Stirling-PDF from 2.13.1 until 2.13.2, the POST /api/v1/convert/svg/pdf endpoint renders attacker-supplied SVG through Apache Batik, and a scheme-less root-relative image reference bypasses SvgSanitizer.isExternalUrl() before Batik resolves it against the file:///input.svg document base as a same-origin local file. The convert() and addSvgAsPage() paths in SvgToPdf.java can then render image-decodable server files into the returned PDF when sanitization is enabled, including without authentication on login-disabled deployments or with non-admin access when login is enabled. The issue discloses PNG, JPG, GIF, or SVG content and provides an existence oracle only for image-decodable paths.

Stirling-PDF 3.0.0 through 3.2.0 contains an authorization bypass that allows authenticated users to access other users' stored files by pointing a processing folder at the server storage directory. Attackers can create a folder via POST /api/v1/processing-folders targeting storage/<victimUserId>, list files, and run pipelines to read, modify, or destroy victims' files.

Stirling-PDF is a locally hosted web application that facilitates various operations on PDF files. Prior to 2.9.0, the /api/v1/pipeline/handleData endpoint injects the STIRLING-PDF-BACKEND-API-USER API key into pipeline subrequests, allowing an authenticated ROLE_USER to retrieve the key through /api/v1/user/get-api-key, impersonate the internal service account, bypass normal rate limits, and access internal endpoints including /api/v1/info/requests/all and /api/v1/info/load/all. This issue is fixed in version 2.9.0.

Stirling-PDF's POST /api/v1/convert/url/pdf endpoint (ConvertWebsiteToPDF.java) was not updated with the CustomHtmlSanitizer/SsrfProtectionService SSRF protections that were added to three sibling conversion endpoints (html/pdf, file/pdf, markdown/pdf).

A vulnerability in Stirling-PDF before version 2.0.0 allowed JavaScript injection via PDF title and author metadata fields. An attacker can craft a malicious PDF that, when its info is viewed in the web interface, executes code in the victim's browser.

Stirling-PDF versions prior to 2.0.0 render user-supplied filenames directly into HTML using unsafe methods like innerHTML without sanitization. An attacker can craft a file with a malicious filename containing JavaScript that executes in the uploading user's browser context, resulting in reflected XSS across numerous upload endpoints.