# CVE-2026-39383: Gotenberg SSRF via Gotenberg-Webhook-Url header

Source: https://junglewise.ai/threats/cve-2026-39383-gotenberg-ssrf-via-gotenberg-webhook-url-header  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-05. Updated: 2026-07-25  
License: CC BY 4.0 with a link back

CVE-2026-39383 · Severity: high · CVSS 7.2 · Published 2026-05-05

Gotenberg is a tool used to convert various file formats into PDFs via an API. A security flaw allows unauthorized users to force the Gotenberg server to send data to unintended internal or external web addresses. This could be used by attackers to map out a company's private internal network or interact with internal services that are not supposed to be accessible from the internet.

Technologies: [github.com/gotenberg/gotenberg/v7 (Go)](https://junglewise.ai/threats/technologies/github-com-gotenberg-gotenberg-v7), [github.com/gotenberg/gotenberg/v8 (Go)](https://junglewise.ai/threats/technologies/github-com-gotenberg-gotenberg-v8), [Gotenberg](https://junglewise.ai/threats/technologies/gotenberg). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Gotenberg](https://junglewise.ai/threats/vendors/gotenberg).

## Quick answers

**Is CVE-2026-39383 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-39383 being exploited in the wild.

**How severe is CVE-2026-39383?** High severity, with a CVSS score of 7.2, published 5 May 2026.

**Which products and versions are affected?** github.com/gotenberg/gotenberg/v7 (Go) SEMVER:introduced=0; github.com/gotenberg/gotenberg/v8 (Go) SEMVER:introduced=8.29.1,fixed=8.31.0; Gotenberg 8.29.1.

**Is there a fix for CVE-2026-39383?** Yes. github.com/gotenberg/gotenberg/v8 (Go): upgrade to 8.31.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-39383 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-39383?** Check whether you run github.com/gotenberg/gotenberg/v7 (Go), github.com/gotenberg/gotenberg/v8 (Go) or Gotenberg at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/gotenberg/gotenberg/v8 (Go): upgrade to 8.31.0 or later

  ```sh
  go get github.com/gotenberg/gotenberg/v8@v8.31.0
  ```


## Technical details

A blind Server-Side Request Forgery (SSRF) exists in Gotenberg version 8.29.1 due to an insecure default configuration in the FilterDeadline function within filter.go. When both the allow-list and deny-list are empty, the function fails open and permits any URL provided in the 'Gotenberg-Webhook-Url' header. An unauthenticated remote attacker can exploit this to send POST requests containing converted documents to arbitrary destinations. While the attacker cannot see the response body, they can perform internal network reconnaissance by monitoring error callbacks and trigger side effects on internal services. The vulnerability is amplified by a retryable HTTP client that issues up to four automatic retries. This issue is fixed in version 8.31.0.

## Affected products

- Gotenberg Gotenberg 8.29.1

## Identifiers

- CVE-2026-39383
- GHSA-5vh4-rgv7-p9g4
- GO-2026-5155

## Timeline

- 2026-04-04: other: Vulnerability discovered
- 2026-04-30: advisory: GitHub Security Advisory published
- 2026-05-05: disclosed: CVE published to NVD
- 2026-08-31: patched: Fixed in version 8.31.0

## References

- [https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5vh4-rgv7-p9g4](https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5vh4-rgv7-p9g4)

## Related threats

- [Gotenberg server-side request forgery in IsPublicIP IPv6 handling](https://junglewise.ai/threats/cve-2026-126799-gotenberg-8-31-0-before-8-38-0-contains-a-server-side-request)
- [Gotenberg race condition in multipart downloadFrom handling](https://junglewise.ai/threats/cve-2026-45742-gotenberg-race-condition-in-multipart-downloadfrom-handling)
- [Gotenberg SSRF deny-list bypass in IsPublicIP via IPv6 prefixes](https://junglewise.ai/threats/cve-2026-45741-gotenberg-ssrf-deny-list-bypass-in-ispublicip-via-ipv6-prefixes)
- [Gotenberg path traversal via Windows-style separators in ZIP entry names](https://junglewise.ai/threats/cve-2026-44829-gotenberg-path-traversal-via-windows-style-separators-in-zip)
- [Gotenberg SSRF and local file disclosure in LibreOffice conversion](https://junglewise.ai/threats/cve-2026-55229-gotenberg-ssrf-and-local-file-disclosure-in-libreoffice)