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Fencer Intel
high 7.5

CVE-2026-40280 json

Gotenberg SSRF via case-insensitive URL scheme bypass in webhook and downloadFrom deny-lists

published 6mo ago modified 3mo ago also EUVD-2026-27476 , GHSA-5q7p-7jgv-ww56 , GO-2026-5151

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 80%
public exploits
0
none known, plus a Nuclei check

Summary

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.

Patch / fix

  • go github.com/gotenberg/gotenberg/v8 8.31.0
  • thecodingmachine gotenberg 8.31.0
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

Is CVE-2026-40280 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
6mo ago

Exploit prediction

1.95% chance of exploitation in the next 30 days, higher than 80% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Nuclei template Gotenberg <= 8.30.1 - Server Side Request Forgery nuclei detection template
  • github.com https://github.com/gotenberg/gotenberg/security/advisories/GHSA-5q7p-7jgv-ww56 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 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
GitHub 3.1 9.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
CNA 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/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
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/gotenberg/gotenberg/v8
<8.31.0
8.31.0
go github.com/gotenberg/gotenberg/v7
all versions
 no fix listed

Affected products

  • gotenberg gotenberg

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.