CVE-2026-42596

Gotenberg: Unauthenticated SSRF via default deny-list bypass in downloadFrom and webhook

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.31.0, the default deny-lists used by Gotenberg's downloadFrom feature and webhook feature are bypassable. Because the filter is regex-based and case-sensitive, an unauthenticated attacker can supply URLs such as http://[::ffff:127.0.0.1]:... and reach loopback or private HTTP services that the default deny-list is intended to block. This crosses a real security boundary because an external caller can force the server to make outbound requests to internal-only targets. This vulnerability is fixed in 8.31.0.

Affected

gotenberg

CVSS v3.1 GITHUB

9.4 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

EPSS

1.77% chance of exploitation in the next 30 days, 78th percentile

Nuclei

critical · CWE-918

Published

2026-05-14

Updated

2026-05-15

Proof-of-concept exploits (1)

• advisories/GHSA-4vmc-gm8v-m35h

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-42596.yaml

Security advisories

• gotenberg/gotenberg/security/advisories/GHSA-4vmc-gm8v-m35h

References

• CVE Record
• NVD entry