CVE-2025-20360
📋 TL;DR
A vulnerability in Cisco's Snort 3 HTTP Decoder allows unauthenticated remote attackers to trigger a denial-of-service condition by sending crafted HTTP packets. This affects Cisco products using Snort 3 for intrusion detection/prevention. The vulnerability stems from incomplete error checking when parsing MIME fields in HTTP headers.
💻 Affected Systems
- Cisco Firepower Threat Defense (FTD)
- Cisco Secure Firewall Management Center
- Other Cisco products using Snort 3
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Continuous exploitation could cause persistent Snort 3 Detection Engine restarts, effectively disabling intrusion detection/prevention capabilities and allowing other attacks to go undetected.
Likely Case
Intermittent Snort 3 restarts causing brief gaps in network security monitoring and potential packet drops during restart periods.
If Mitigated
Minimal impact with proper network segmentation and monitoring; Snort 3 automatically recovers after restart.
🎯 Exploit Status
Exploitation requires sending specifically crafted HTTP packets through an established connection. No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Snort 3 version 3.2.0.0 or later
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort3-mime-vulns-tTL8PgVH
Restart Required: Yes
Instructions:
1. Review Cisco advisory for specific product updates. 2. Download appropriate patches from Cisco Software Center. 3. Apply updates following Cisco's upgrade procedures. 4. Verify Snort 3 version is 3.2.0.0 or higher.
🔧 Temporary Workarounds
Disable HTTP Inspection
allTemporarily disable HTTP inspection in Snort 3 policies to prevent exploitation while patching.
# Modify Snort 3 policy to exclude HTTP inspection
# Consult Cisco documentation for specific policy modification commands
🧯 If You Can't Patch
- Implement network segmentation to limit HTTP traffic to Snort 3 instances
- Deploy network monitoring to detect repeated Snort 3 restarts and anomalous HTTP traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check Snort 3 version: 'show version' on Cisco devices or 'snort --version' on standalone installations. Versions below 3.2.0.0 are vulnerable.Check Version:
show version | include SnortVerify Fix Applied:
Verify Snort 3 version is 3.2.0.0 or higher using version check commands. Monitor system logs for Snort 3 restart events.📡 Detection & Monitoring
Log Indicators:
- Snort 3 process restart events
- Unexpected Snort 3 termination logs
- Increased restart frequency in system logs
Network Indicators:
- Unusual HTTP traffic patterns with malformed MIME headers
- Gaps in intrusion detection alerts
SIEM Query:
source="*snort*" AND ("restart" OR "terminated unexpectedly" OR "segmentation fault")