CVE-2019-25048
📋 TL;DR
This vulnerability in LibreSSL allows attackers to read beyond allocated heap memory boundaries when processing ASN.1 data structures. It affects systems using LibreSSL 2.9.1 through 3.2.1 for cryptographic operations, potentially exposing sensitive information from memory.
💻 Affected Systems
- LibreSSL
📦 What is this software?
Libressl by Openbsd
⚠️ Risk & Real-World Impact
Worst Case
Information disclosure of sensitive cryptographic keys, certificates, or other memory contents leading to complete system compromise.
Likely Case
Application crash (denial of service) or limited information disclosure from adjacent memory regions.
If Mitigated
Minimal impact if systems are patched or don't process untrusted ASN.1 data.
🎯 Exploit Status
Exploitation requires control over ASN.1 data passed to vulnerable printing functions. The OSS-Fuzz bug report contains triggering inputs.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: LibreSSL 3.2.2 and later
Vendor Advisory: https://ftp.openbsd.org/pub/OpenBSD/LibreSSL/libressl-3.2.2-relnotes.txt
Restart Required: Yes
Instructions:
1. Update LibreSSL to version 3.2.2 or later. 2. Recompile applications linked against LibreSSL. 3. Restart affected services.
🔧 Temporary Workarounds
Disable ASN.1 Debug Output
allAvoid calling vulnerable ASN.1 printing functions in production code.
Review application code and remove/disable calls to ASN1_item_print and related functions
🧯 If You Can't Patch
- Restrict input to ASN.1 parsing functions to trusted sources only
- Implement strict input validation and bounds checking for ASN.1 data processing
🔍 How to Verify
Check if Vulnerable:
Check LibreSSL version: libressl version | grep -E '2\.9\.1|3\.0\.|3\.1\.|3\.2\.0|3\.2\.1'Check Version:
libressl versionVerify Fix Applied:
Verify version is 3.2.2 or later: libressl version | grep -E '3\.2\.2|3\.3\.'📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults in LibreSSL ASN.1 functions
- Unexpected memory access errors in security logs
Network Indicators:
- Unusual ASN.1 data patterns sent to services using LibreSSL
SIEM Query:
source="*libressl*" AND ("segmentation fault" OR "heap overflow" OR "ASN1_item_print")🔗 References
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13914
- https://github.com/google/oss-fuzz-vulns/blob/main/vulns/libressl/OSV-2020-1923.yaml
- https://github.com/libressl-portable/portable/commit/17c88164016df821df2dff4b2b1291291ec4f28a
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=13914
- https://github.com/google/oss-fuzz-vulns/blob/main/vulns/libressl/OSV-2020-1923.yaml
- https://github.com/libressl-portable/portable/commit/17c88164016df821df2dff4b2b1291291ec4f28a
