CVE-2026-42596Public exploitNetwork attack vector

Unauthenticated SSRF via case-sensitive deny-list bypass

Published May 14, 2026 · Updated May 14, 2026

SSRF in Gotenberg before 8.31.0 allows remote attackers to reach internal HTTP services through downloadFrom and webhook URLs. The default regexes in api.go and webhook.go match case-sensitively before filter.go passes attacker-controlled URLs to Go HTTP clients, so IPv4-mapped IPv6 loopback forms evade the private-address patterns. Any unauthenticated caller able to reach the API can read internal responses through downloadFrom or trigger state-changing webhook requests to loopback and private services.

CVSS severity9.4
Critical
EPSS probability1.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in Gotenberg before 8.31.0 allows remote attackers to reach internal HTTP services through downloadFrom and webhook URLs. The default regexes in api.go and webhook.go match case-sensitively before filter.go passes attacker-controlled URLs to Go HTTP clients, so IPv4-mapped IPv6 loopback forms evade the private-address patterns. Any unauthenticated caller able to reach the API can read internal responses through downloadFrom or trigger state-changing webhook requests to loopback and private services.

The record

CVE
CVE-2026-42596
Published
May 14, 2026
Updated
May 14, 2026
Vendor
Gotenberg
Product
Gotenberg
Classifications
CWE-918, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 14, 2026CVE publishedPublication date reported by the CVE source.
  2. May 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 8.31.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Gotenberg · Gotenbergversion=< 8.31.0

Published CVSS scores

9.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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