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Vulnerability record · CVE-2026-40280 · published 5 May 2026

CVE-2026-40280: Thecodingmachine gotenberg server-side request forgery (ssrf) vulnerability

Thecodingmachine · Gotenberg

Gotenberg is an API-based document conversion tool. In versions 8.30.1 and earlier, the default private-IP deny-lists for the --webhook-deny-list and --api-download-from-deny-list flags use a case-sensitive regular expression (^https?://) to match URL schemes. Because Go's net/url.Parse() normalizes the scheme to lowercase before establishing the outbound TCP connection, an attacker can bypass the deny-list by simply capitalizing part of the URL scheme (e.g., HTTP://, HTTPS://, or Http://). This allows unauthenticated requests to reach internal network services, including private IP ranges, loopback addresses, and cloud instance metadata endpoints such as HTTP://169.254.169.254/latest/meta-data/. This bypasses the same security control that was patched in CVE-2026-27018. This issue has been fixed in version 8.31.0.

7.8 CVSS 4.0 High EPSS 2.1% · top 18.9% CWE-918 · Server-side request forgery (SSRF)
7.8CVSS 4.0 base score
2.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
24 Jul 2026Last modified by NVD

Description

Gotenberg is an API-based document conversion tool. In versions 8.30.1 and earlier, the default private-IP deny-lists for the --webhook-deny-list and --api-download-from-deny-list flags use a case-sensitive regular expression (^https?://) to match URL schemes. Because Go's net/url.Parse() normalizes the scheme to lowercase before establishing the outbound TCP connection, an attacker can bypass the deny-list by simply capitalizing part of the URL scheme (e.g., HTTP://, HTTPS://, or Http://). This allows unauthenticated requests to reach internal network services, including private IP ranges, loopback addresses, and cloud instance metadata endpoints such as HTTP://169.254.169.254/latest/meta-data/. This bypasses the same security control that was patched in CVE-2026-27018. This issue has been fixed in version 8.31.0.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/advisories/GHSA-jjwv-57xh-xr6r Not Applicable
https://github.com/gotenberg/gotenberg/commit/3f01ca18d3cc21375a1e2da4b5a3f261c8548e47 Patch
https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5q7p-7jgv-ww56 ExploitMitigationVendor Advisory
https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5q7p-7jgv-ww56 ExploitMitigationVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2026-42589Thecodingmachine gotenberg os command injection vulnerabilityGotenberg is a Docker-powered stateless API for PDF files. Prior to 8.31.0, Gotenberg's /forms/pdfengines/metadata/write HTTP endpoint accepts a JSON…EPSS 3.7%9.8CVE-2020-13452Thecodingmachine gotenberg incorrect default permissions vulnerabilityIn Gotenberg through 6.2.1, insecure permissions for tini (writable by user gotenberg) potentially allow an attacker to overwrite the file, which can…EPSS 2.7%9.8CVE-2020-13450Thecodingmachine gotenberg path traversal vulnerabilityA directory traversal vulnerability in file upload function of Gotenberg through 6.2.1 allows an attacker to upload and overwrite any writable files …EPSS 5.6%9.8CVE-2020-13451Thecodingmachine gotenberg vulnerabilityAn incomplete-cleanup vulnerability in the Office rendering engine of Gotenberg through 6.2.1 allows an attacker to overwrite LibreOffice configurati…EPSS 3.0%9.4CVE-2026-42596Thecodingmachine gotenberg server-side request forgery (ssrf) vulnerabilityGotenberg 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 webho…EPSS 1.8%9.1CVE-2026-40281Thecodingmachine gotenberg argument injection vulnerabilityGotenberg is a Docker-powered stateless API for PDF files. In versions 8.30.1 and earlier, the metadata write endpoint validates metadata keys for co…EPSS 0.66%8.7CVE-2026-35458Thecodingmachine gotenberg inefficient regular expression (redos) vulnerabilityGotenberg is an API for converting document formats. In 8.29.1 and earlier, Gotenberg uses dlclark/regexp2 to compile user-supplied scope patterns wi…EPSS 0.61%8.6CVE-2026-42595Thecodingmachine gotenberg server-side request forgery (ssrf) vulnerabilityGotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, Gotenberg's Chromium URL-to-PDF endpoint (/forms/chromium/convert/url) ha…EPSS 0.42%

Source: NIST National Vulnerability Database (record CVE-2026-40280), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.