CVE-2026-40280
HighPublic exploitGotenberg has case-insensitive URL scheme that bypasses webhook and downloadFrom deny-list SSRF protection
Published Apr 30, 2026 · Updated Aug 12, 2026 · Also known as GHSA-5q7p-7jgv-ww56, GO-2026-5151
Key Facts
Patch immediately- CVE-2026-40280 is a high-severity vulnerability (CVSS 7.8 v4) affecting Gotenberg (Thecodingmachine), github.com/gotenberg/gotenberg/v7 (go), github.com/gotenberg/gotenberg/v8 (go).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 2.1% probability of exploitation in the next 30 days.
- Fixed versions are available, including github.com/gotenberg/gotenberg/v8 8.31.0, Gotenberg 8.31.0.
- Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
CVSS v4
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (30-day exploit likelihood)
2.1%
Higher than 81.5% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2026-40280 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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.
Affected Products
4 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| GotenbergThecodingmachine | >= <= 8.30.1 | 8.31.0 |
| github.com/gotenberg/gotenberg/v7go | See advisory | n/a |
| github.com/gotenberg/gotenberg/v8go | See advisory | 8.31.0 |
Patched Releases
github.com/gotenberg/gotenberg/v8
8.31.0
Gotenberg
8.31.0
Timeline
Publicly disclosed
Apr 30, 2026
Last updated
Aug 12, 2026
Weakness Type
- CWE-918 Server-Side Request Forgery (SSRF)
References
- advisoryGHSA advisory
- advisoryhttps://github.com/advisories/GHSA-jjwv-57xh-xr6r
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40280.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-40280
- articlehttps://github.com/gotenberg/gotenberg/commit/3f01ca18d3cc21375a1e2da4b5a3f261c8548e47
FAQ
Common Questions.
Gotenberg is an API-based document conversion tool.
Affected: Gotenberg (Thecodingmachine) versions >= <= 8.30.1; github.com/gotenberg/gotenberg/v7 (go); github.com/gotenberg/gotenberg/v8 (go). The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including github.com/gotenberg/gotenberg/v8 8.31.0, Gotenberg 8.31.0.
Brandefense priority: patch immediately, because public exploit code exists for a high-severity flaw.
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