CVE-2025-48965
📋 TL;DR
This vulnerability in Mbed TLS allows an attacker to cause a denial of service (DoS) by triggering a NULL pointer dereference when parsing malformed ASN.1 data. It affects systems using Mbed TLS for cryptographic operations, particularly those processing untrusted certificates or ASN.1 data. The impact is limited to service crashes rather than code execution.
💻 Affected Systems
- Mbed TLS
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service crash leading to denial of service for applications relying on Mbed TLS for cryptographic operations.
Likely Case
Service instability or crashes when processing malformed certificates or ASN.1 data from untrusted sources.
If Mitigated
Minimal impact if proper input validation and error handling are in place, or if affected systems don't process untrusted ASN.1 data.
🎯 Exploit Status
Exploitation requires sending malformed ASN.1 data to trigger the NULL pointer dereference. No authentication needed if system processes external ASN.1 data.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.6.4
Vendor Advisory: https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-security-advisory-2025-06-6.md
Restart Required: Yes
Instructions:
1. Download Mbed TLS 3.6.4 or later from official repository. 2. Replace existing Mbed TLS installation with patched version. 3. Recompile any applications using Mbed TLS. 4. Restart affected services.
🔧 Temporary Workarounds
Input Validation Filter
allImplement additional validation for ASN.1 data before passing to Mbed TLS functions
Service Restart Automation
linuxConfigure automatic service restart on crash to minimize DoS impact
🧯 If You Can't Patch
- Implement network filtering to block malformed ASN.1 data at perimeter
- Deploy monitoring to detect and alert on repeated service crashes
🔍 How to Verify
Check if Vulnerable:
Check Mbed TLS version with: mbedtls_version -v or examine library files for version < 3.6.4Check Version:
mbedtls_version -v 2>/dev/null || strings /usr/lib/libmbedtls* | grep -i versionVerify Fix Applied:
Verify version is 3.6.4 or higher and test ASN.1 parsing functionality📡 Detection & Monitoring
Log Indicators:
- Segmentation fault errors
- Unexpected service termination
- ASN.1 parsing errors
Network Indicators:
- Unusual ASN.1 data patterns
- Repeated connection attempts with malformed certificates
SIEM Query:
source="application.logs" AND ("segmentation fault" OR "null pointer" OR "mbedtls crash")