GHSA-3cv5-q585-h563 MEDIUM go/github.com/gotenberg/gotenberg/v8

CVE: CVE-2026-42593

Summary

Six conversion routes (pdfengines/merge, pdfengines/split, libreoffice/convert, chromium/convert/url, chromium/convert/html, chromium/convert/markdown) accept stampSource=pdf + stampExpression=/path and watermarkSource=pdf + watermarkExpression=/path from anonymous callers. The dedicated stamp/watermark routes require an uploaded file when the source type is image or pdf; these six routes only overwrite the expression when a file is uploaded, leaving the user-controlled path intact when no file is attached. pdfcpu opens the path and composites its pages onto the output PDF, which returns to the caller. An attacker reads any PDF the Gotenberg process can access on the container filesystem.

Details

The dedicated stamp route at pkg/modules/pdfengines/routes.go:1322-1332 rejects requests missing the stamp file:

if stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF {
    if stampFile == "" {
        return api.WrapError(errors.New("no stamp file provided"), ...)
    }
    stamp.Expression = stampFile
}

The merge, split, LibreOffice, and Chromium routes use a lax pattern across twelve call sites (six stamp + six watermark):

// pkg/modules/pdfengines/routes.go:679-683 (merge), 803 (split);
// pkg/modules/libreoffice/routes.go:307-311;
// pkg/modules/chromium/routes.go:433-438, 508-513, 592-597
if (stamp.Source == gotenberg.StampSourceImage || stamp.Source == gotenberg.StampSourcePDF) && stampFile != "" {
    stamp.Expression = stampFile
}
if (watermark.Source == gotenberg.StampSourceImage || watermark.Source == gotenberg.StampSourcePDF) && watermarkFile != "" {
    watermark.Expression = watermarkFile
}

When stampFile == "" (no file attached to the stamp form field), the guard short-circuits and stamp.Expression keeps the raw user-supplied stampExpression form string. The same pattern applies to watermarkFile/watermarkExpression.

`pkg/modules/pdfcpu/pdfcpu.go:635

📌 来源: GitHub-Advisory | 🆔 CVE-2026-42593 | 📅 2026-05-07