CVE-2026-42596

CVE-2026-42596 is a critical-severity vulnerability in Thecodingmachine Gotenberg with a CVSS 3.x base score of 9.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-918.

Key facts

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.

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.
How severe is CVE-2026-42596?
CVE-2026-42596 has a CVSS 3.x base score of 9.4, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2026-42596 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42596?
CVE-2026-42596 affects Thecodingmachine Gotenberg. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42596?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-42596 have an EU (EUVD) identifier?
Yes. CVE-2026-42596 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30310.
When was CVE-2026-42596 published?
CVE-2026-42596 was published on 2026-05-14 and last updated on 2026-06-17.

References

Affected products (1)

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