CVE-2026-61741 — http4s-scala-xml provides `EntityDecoder[F, scala.xml.Elem]` instances that parse XML…¶

Key facts

CVE-2026-61741 is a Critical (9.3) vulnerability: http4s-scala-xml provides EntityDecoder[F, scala.xml.Elem] instances that parse XML…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-61741
Severity	Critical (9.3)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-61741/

Details¶

English | 한국어

Description¶

http4s-scala-xml provides EntityDecoder[F, scala.xml.Elem] instances that parse XML message bodies. Prior to versions 0.24.1 and 1.0.0-M39, these decoders used a javax.xml.parsers.SAXParserFactory obtained from SAXParserFactory.newInstance without any security configuration. With the JDK's default settings, the parser resolves DOCTYPE declarations, external general and parameter entities, and external DTDs.An application that uses these decoders to parse untrusted XML is vulnerable to XML External Entity (XXE) attacks. An attacker can craft a request that discloses local files readable by the service process, performs server-side request forgery (SSRF) against internal network resources, and/or causes denial of service through entity expansion. Versions 0.24.1 and 1.0.0-M39 fix the issue.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-61741
Type	SSRF
CVSS Score	9.3

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-61741/poc.py

Usage¶

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab¶

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start¶

# Clone and navigate to CVE directory
cd CVE-2026-61741

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints¶

Application	URL	Status
Vulnerable App	http://localhost:8080	Shows vulnerability
Patched App	http://localhost:8081	Demonstrates fix

Directory Structure¶

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References¶

https://github.com/http4s/http4s-scala-xml/security/advisories/GHSA-cjx3-73hr-rpw7

Generated by PoC Generator on 2026-09-27T11:19:34.334535168

Frequently asked questions¶

What is CVE-2026-61741?¶