Gotenberg has arbitrary PDF read via stampExpression and watermarkExpression in merge, split, and convert routes

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-42593: 0.31% estimated exploitation activity in the next 30 days; percentile 24.01 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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: The merge, split, LibreOffice, and Chromium routes use a lax pattern across twelve call sites (six stamp + six watermark): When stampFile == "" (no file attached to the…

Published by the source

7 May 2026, 00:59 UTC

Last modified by the source

14 May 2026, 20:52 UTC

Source last checked

26 Oct 2026, 15:22 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3cv5-q585-h563

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# Patch Next advisory brief: CVE-2026-42593

Advisory: Gotenberg has arbitrary PDF read via stampExpression and watermarkExpression in merge, split, and convert routes
IDs: CVE-2026-42593, GHSA-3cv5-q585-h563
Record: https://patchnext.com/advisories/cve-2026-42593 (revision 1, source checked 26 Oct 2026, 15:22 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/gotenberg/gotenberg/v8: affected <= 8.31.0

## Suggested inspection (read-only)
- Go github.com/gotenberg/gotenberg/v8: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/gotenberg/gotenberg/v8.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-3cv5-q585-h563 (GitHub-reviewed advisory GHSA-3cv5-q585-h563 lists affected ranges: Go github.com/gotenberg/gotenberg/v8 >=0 <=8.31.0)

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