CVE-2025-27520
📋 TL;DR
CVE-2025-27520 is a critical remote code execution vulnerability in BentoML caused by insecure deserialization in serde.py. It allows unauthenticated attackers to execute arbitrary code on servers running vulnerable versions. All users of BentoML versions up to 1.4.2 are affected.
💻 Affected Systems
- BentoML
📦 What is this software?
Bentoml by Bentoml
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the server, data exfiltration, lateral movement, and persistent backdoor installation.
Likely Case
Server takeover leading to data theft, cryptocurrency mining, or use as part of a botnet for DDoS attacks.
If Mitigated
Limited impact if proper network segmentation and least privilege principles are implemented, though RCE still poses significant risk.
🎯 Exploit Status
The vulnerability requires no authentication and exploits insecure deserialization, which typically has low exploitation complexity.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.3
Vendor Advisory: https://github.com/bentoml/BentoML/security/advisories/GHSA-33xw-247w-6hmc
Restart Required: Yes
Instructions:
1. Stop all BentoML services. 2. Update BentoML using pip: pip install --upgrade bentoml==1.4.3. 3. Restart all BentoML services.
🔧 Temporary Workarounds
Network Isolation
linuxRestrict network access to BentoML services to trusted IPs only
iptables -A INPUT -p tcp --dport <bentoml_port> -s <trusted_ip> -j ACCEPT
iptables -A INPUT -p tcp --dport <bentoml_port> -j DROP
🧯 If You Can't Patch
- Implement strict network segmentation and firewall rules to limit access to BentoML services
- Deploy web application firewall (WAF) with deserialization attack detection rules
🔍 How to Verify
Check if Vulnerable:
Check BentoML version: python -c "import bentoml; print(bentoml.__version__)"Check Version:
python -c "import bentoml; print(bentoml.__version__)"Verify Fix Applied:
Verify version is 1.4.3 or higher: python -c "import bentoml; assert bentoml.__version__ >= '1.4.3', 'Vulnerable version'"📡 Detection & Monitoring
Log Indicators:
- Unusual process spawns from BentoML services
- Suspicious deserialization attempts in application logs
- Unexpected network connections from BentoML processes
Network Indicators:
- Malformed serialization payloads to BentoML endpoints
- Unusual outbound connections from BentoML servers
SIEM Query:
source="bentoml.logs" AND ("deserialization" OR "pickle" OR "yaml.load")