SSRF in Gotenberg
CVE-2026-40280
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.
Vulnerability class: SSRF (Server-Side Request Forgery)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.021 (81.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 81st percentile — 81.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.016 · newest: 0.021 · change: +0.006
Affected products
- Gotenberg — versions <= 8.30.1
- Thecodingmachine Gotenberg
Weakness classification (CWE)
References
- github.com/gotenberg/gotenberg/security/advisories/GHSA-5q7p-7jgv-ww56 (Exploit, Mitigation, Vendor Advisory)
- github.com/gotenberg/gotenberg/commit/3f01ca18d3cc21375a1e2da4b5a3f261c8548e47 (Patch)
- github.com/advisories/GHSA-jjwv-57xh-xr6r (Not Applicable)
Frequently asked questions
- What is CVE-2026-40280?
- CVE-2026-40280 is a high-severity vulnerability in Gotenberg, classified under Server-Side Request Forgery (SSRF). CVSS score: 7.5/10. Published 2026-05-05.
- How severe is CVE-2026-40280?
- High severity. CVSS v3 base score is 7.5 out of 10.