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CVE-2026-42596— Gotenberg: Unauthenticated SSRF via default deny-list bypass in downloadFrom and webhook

Quick assessment

Affected
gotenberg gotenberg
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Gotenberg是Gotenberg开源的一个开发人员友好的 API。用于将多种文档格式转换为 PDF 文件。 Gotenberg 8.31.0之前版本存在代码问题漏洞，该漏洞源于默认拒绝列表基于正则表达式且区分大小写，允许攻击者通过IPv6映射地址绕过限制，访问内部HTTP服务。

CVSS 9.4 · Critical EPSS 1.77% · P78

Public Exploits 1

Nuclei · 1 CVE-2026-42596.yaml [template]

Affected Version Matrix 1

VendorProduct Version RangeStatus
gotenberg gotenberg < 8.31.0 affected
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I. Basic Information for CVE-2026-42596

Vulnerability Information
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Vulnerability Title
Gotenberg: Unauthenticated SSRF via default deny-list bypass in downloadFrom and webhook
Source: CVE Program / CVE List V5
Vulnerability Description
Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.31.0, the default deny-lists used by Gotenberg's downloadFrom feature and webhook feature are bypassable. Because the filter is regex-based and case-sensitive, an unauthenticated attacker can supply URLs such as http://[::ffff:127.0.0.1]:... and reach loopback or private HTTP services that the default deny-list is intended to block. This crosses a real security boundary because an external caller can force the server to make outbound requests to internal-only targets. This vulnerability is fixed in 8.31.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
Source: CVE Program / CVE List V5
Vulnerability Title
Gotenberg 代码问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Gotenberg是Gotenberg开源的一个开发人员友好的 API。用于将多种文档格式转换为 PDF 文件。 Gotenberg 8.31.0之前版本存在代码问题漏洞，该漏洞源于默认拒绝列表基于正则表达式且区分大小写，允许攻击者通过IPv6映射地址绕过限制，访问内部HTTP服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
gotenberg gotenberg < 8.31.0 -

II. Public POCs for CVE-2026-42596

# POC Description Source Link Shenlong Link
1 Gotenberg before 8.31.0 is vulnerable to server-side request forgery (SSRF) due to insufficient validation of URLs in the downloadFrom API. An unauthenticated attacker can exploit the flaw by providing specially crafted IPv4-mapped IPv6 addresses (such as http://[::ffff:127.0.0.1]) that bypass the deny-list and allow access to internal resources. Fixed versions properly recognize these addresses and prevent such requests. https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-42596.yaml POC Details
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III. Intelligence Information for CVE-2026-42596

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Vendor Advisories for CVE-2026-42596 (1)

Same Patch Batch · gotenberg · 2026-05-14 · 10 CVEs total

CVE-2026-42589 9.8 CRITICAL Gotenberg: Unauthenticated RCE via ExifTool Metadata Key Injection
CVE-2026-42595 8.6 HIGH Gotenberg: Server-Side Request Forgery via Chromium URL Endpoint with Redirect-Based Deny-
CVE-2026-42591 8.2 HIGH Gotenberg: Server-Side Request Forgery (SSRF) in github.com/gotenberg/gotenberg/v8
CVE-2026-42590 8.2 HIGH Gotenberg: ExifTool group-prefix syntax bypasses dangerous-tag blocklist
CVE-2026-40893 8.2 HIGH Gotenberg: ExifTool Dangerous Tag Blocklist Bypass via Group-Prefixed Tag Names Allows Arb
CVE-2026-42594 7.5 HIGH Gotenberg: Unauthenticated denial of service via echo.Context pool reuse in webhook async
CVE-2026-42597 5.9 MEDIUM Gotenberg: Chromium URL conversion routes read arbitrary files under /tmp via file:// sche
CVE-2026-42593 5.3 MEDIUM Gotenberg: Arbitrary PDF read via stampExpression and watermarkExpression in merge, split,
CVE-2026-42592 5.3 MEDIUM Gotenberg: DNS rebinding bypasses SSRF validation on Chromium URL conversion routes

IV. Related Vulnerabilities

Same product: gotenberg
Same vendor: gotenberg
Same weakness: CWE-918

V. Comments for CVE-2026-42596

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