Gotenberg has case-insensitive URL scheme that bypasses webhook and downloadFrom deny-list SSRF protection

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

7.8 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N · score source

EPSS

• CVE-2026-40280: 1.95% estimated exploitation activity in the next 30 days; percentile 80.25 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Vulnerability Details CWE: CWE-918 - Server-Side Request Forgery (SSRF) The default private-IP deny-lists for --webhook-deny-list and --api-download-from-deny-list use a case-sensitive regex (^https?://). Any uppercase URL scheme variant (HTTP://, HTTPS://, Http://) bypasses the pattern. Go's net/url.Parse() normalizes the scheme to lowercase when making the outbound TCP connection, so the connection succeeds normally. Affected: pkg/gotenberg/filter.go:FilterDeadline(), pkg/modules/webhook/webhook.go:42, pkg/modules/api/api.go:199. Confirmed in Docker: http://172.17.0.1:12345/ returns HTTP 403 (blocked), HTTP://172.17.0.1:12345/ returns HTTP 202 (bypassed, TCP connection attempted). Same pattern as CVE-2026-27018/GHSA-jjwv-57xh-xr6r but in newly added webhook+downloadFrom deny-lists (commit 3f01ca1, 2026-04-07). Affected versions: <= 8.30.1. CVSS: AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N = 9.1. Summary The default private-IP deny-lists for --webhook-deny-list and…

Published by the source

30 Apr 2026, 17:19 UTC

Last modified by the source

8 May 2026, 15:31 UTC

Source last checked

26 Oct 2026, 15:20 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-5q7p-7jgv-ww56

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# Patch Next advisory brief: CVE-2026-40280

Advisory: Gotenberg has case-insensitive URL scheme that bypasses webhook and downloadFrom deny-list SSRF protection
IDs: CVE-2026-40280, GHSA-5q7p-7jgv-ww56
Record: https://patchnext.com/advisories/cve-2026-40280 (revision 1, source checked 26 Oct 2026, 15:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/gotenberg/gotenberg/v8 8.31.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/gotenberg/gotenberg/v8: affected <= 8.30.1; fixed in 8.31.0

## Suggested inspection (read-only)
- Go github.com/gotenberg/gotenberg/v8: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/gotenberg/gotenberg/v8.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-5q7p-7jgv-ww56 (GitHub-reviewed advisory GHSA-5q7p-7jgv-ww56 lists affected ranges: Go github.com/gotenberg/gotenberg/v8 >=0 <=8.30.1)

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