Vulnerability 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 Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Thecodingmachine | Gotenberg | < 8.31.0 |
Related Weaknesses (CWE)
References
- https://github.com/advisories/GHSA-jjwv-57xh-xr6rNot Applicable
- https://github.com/gotenberg/gotenberg/commit/3f01ca18d3cc21375a1e2da4b5a3f261c8Patch
- https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5q7p-7jgv-ww56ExploitMitigationVendor Advisory
- https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5q7p-7jgv-ww56ExploitMitigationVendor Advisory
FAQ
What is CVE-2026-40280?
CVE-2026-40280 is a vulnerability with a CVSS score of 7.5 (HIGH). 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-sen...
How severe is CVE-2026-40280?
CVE-2026-40280 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-40280?
Check the references section above for vendor advisories and patch information. Affected products include: Thecodingmachine Gotenberg.