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.
Problem types
CWE-918: Server-Side Request Forgery (SSRF)
Product status
References
github.com/…enberg/security/advisories/GHSA-5q7p-7jgv-ww56
github.com/…ommit/3f01ca18d3cc21375a1e2da4b5a3f261c8548e47
github.com/advisories/GHSA-jjwv-57xh-xr6r
