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Advisory record · GHSA-4vmc-gm8v-m35h

Gotenberg vulnerable to unauthenticated SSRF via default deny-list bypass in downloadFrom and webhook

CVSS 9.4 CriticalCriticalEPSS 0.016 · 76th percentile

Critical, because:

  • CVSS score 9.4: 9.0 or more.

How we decide what’s critical

Published by the GitHub Advisory Database at 7 May 2026, 01:15 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/gotenberg/gotenberg/v8Go<8.32.08.32.0
Identifiers
GHSA-4vmc-gm8v-m35h · CVE-2026-42596 · GO-2026-5132
Weakness (CWE)
CWE-918
Tags
Published
7 May 2026
Updated
25 Jun 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Gotenberg versions before 8.32.0 are affected. The default deny-lists for the downloadFrom and webhook features use case-sensitive regex matching, so URLs such as ones using the IPv4-mapped IPv6 form of loopback addresses can bypass them. An unauthenticated attacker who can reach the instance can make it send outbound requests to loopback and private services, reading content through downloadFrom or triggering requests through webhooks. Upgrade to Gotenberg 8.32.0 or later. The source gives no workaround.

Written 7 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.4 Critical 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.016, the 76th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 14 May 2026, 16:16 UTC Confirmed by NVD
  2. 31 Oct 2026, 15:07 UTC First seen by agentprime
  3. 31 Oct 2026, 15:07 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.