CVE-2025-14819
📋 TL;DR
A TLS certificate validation vulnerability in libcurl where reusing easy or multi handles with altered CURLSSLOPT_NO_PARTIALCHAIN options could cause libcurl to incorrectly reuse cached CA stores with reversed partial chain settings. This could allow libcurl to accept trust chains it should reject, potentially enabling man-in-the-middle attacks. Affects applications using libcurl with TLS connections and handle reuse.
💻 Affected Systems
- libcurl
- curl
- applications using libcurl library
📦 What is this software?
Curl by Haxx
curl is a command-line tool and library for transferring data with URLs. It supports numerous protocols including HTTP, HTTPS, FTP, and more, making it essential for API testing, web scraping, and automated data transfers.
Learn more about Curl →⚠️ Risk & Real-World Impact
Worst Case
Man-in-the-middle attackers could intercept and decrypt TLS traffic by presenting certificates that should be rejected due to partial chain validation issues, potentially compromising sensitive data in transit.
Likely Case
Limited impact in most scenarios as exploitation requires specific handle reuse patterns and attacker positioning, but could affect applications with complex TLS configurations and handle management.
If Mitigated
Minimal impact if applications don't reuse handles with altered SSL options or if proper certificate pinning and validation is implemented.
🎯 Exploit Status
Exploitation requires specific handle reuse patterns and ability to position as man-in-the-middle. No public exploits known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: libcurl 8.10.0
Vendor Advisory: https://curl.se/docs/CVE-2025-14819.html
Restart Required: Yes
Instructions:
1. Upgrade libcurl to version 8.10.0 or later. 2. Recompile applications using libcurl if statically linked. 3. Restart affected services using libcurl.
🔧 Temporary Workarounds
Avoid handle reuse with SSL option changes
allDo not reuse easy or multi handles when changing CURLSSLOPT_NO_PARTIALCHAIN option between uses
Disable handle caching
allConfigure applications to not cache or reuse curl handles when SSL options vary
🧯 If You Can't Patch
- Implement certificate pinning to validate expected certificates
- Use separate curl handles for connections with different SSL option requirements
🔍 How to Verify
Check if Vulnerable:
Check libcurl version with 'curl --version' or examine application's linked libcurl version. Versions 8.8.0 to 8.9.0 are vulnerable.Check Version:
curl --version | head -1Verify Fix Applied:
Verify libcurl version is 8.10.0 or later. Test TLS connections with partial chain certificates to ensure proper validation.📡 Detection & Monitoring
Log Indicators:
- Unexpected certificate validation successes with partial chains
- TLS handshake anomalies in application logs
Network Indicators:
- Unusual certificate chains in TLS traffic
- MITM detection alerts
SIEM Query:
Search for curl/libcurl version strings 8.8.0-8.9.0 in asset inventory or package management logs