CVE-2026-42596

Description

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.

CVSS v3.1 Score

9.4

CRITICAL

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

EPSS — Exploit Prediction

0.0008

Probability of exploitation

0.24%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-918 Server-Side Request Forgery (SSRF)

Affected Products

Vendor	Product	Versions
thecodingmachine	gotenberg	< 8.31.0

References

Advisories & Patches

https://github.com/gotenberg/gotenberg/security/advisories/GHSA-4vmc-gm8v-m35h https://github.com/gotenberg/gotenberg/security/advisories/GHSA-4vmc-gm8v-m35h

Exploits

https://github.com/gotenberg/gotenberg/security/advisories/GHSA-4vmc-gm8v-m35h https://github.com/gotenberg/gotenberg/security/advisories/GHSA-4vmc-gm8v-m35h

Frequently Asked Questions

What is CVE-2026-42596? +

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. It has a CVSS v3.1 base score of 9.4 (CRITICAL).

How severe is CVE-2026-42596? +

CVE-2026-42596 has a CVSS v3.1 score of 9.4 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0008, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-42596? +

CVE-2026-42596 affects products from thecodingmachine, specifically: gotenberg. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-42596? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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