Gotenberg <= 8.30.1 - Server Side Request Forgery
CVE-2026-40280
Verified
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.
Severity
Critical
CVSS Score
9.3
Exploit Probability
2%
Affected Product
gotenberg
Published Date
August 6, 2026
Template Author
str4k3r
CVE-2026-40280.yaml
9.3Score
CVSS Metrics
CVSS Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
CVE ID:
cve-2026-40280
CWE ID:
cwe-918
Remediation Steps
This bypasses the same security control that was patched in CVE-2026-27018. This issue has been fixed in version 8.31.0.