CVE-2026-40280

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

1.9% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-05-05 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-24 21:10 UTC Last updatedMost recent change to the record

Details

Published

2026-05-05 20:16 UTC

Last modified

2026-07-24 21:10 UTC

Exploit probability

1.9% · EPSS, next 30 days

Weakness

CWE-918 · Server-side request forgery

Record status

Analyzed

Affected

• Thecodingmachine Gotenberg < 8.31.0

Attack profile CVSS 4.0 · 7.8

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

None

Integrity

None

Availability

None