CVE-2026-25949
📋 TL;DR
This vulnerability allows unauthenticated attackers to cause denial of service in Traefik reverse proxy by exploiting a STARTTLS timeout bypass. Attackers can send a specific 8-byte Postgres SSLRequest and then stall, keeping connections open indefinitely and exhausting resources. All Traefik deployments prior to version 3.6.8 are affected.
💻 Affected Systems
- Traefik
📦 What is this software?
Traefik by Traefik
⚠️ Risk & Real-World Impact
Worst Case
Complete service unavailability due to connection pool exhaustion, affecting all traffic through the Traefik proxy
Likely Case
Degraded performance and intermittent service disruptions as connections accumulate
If Mitigated
Minimal impact with proper network segmentation and connection limits
🎯 Exploit Status
Simple network-level attack requiring minimal technical skill to execute
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.6.8
Vendor Advisory: https://github.com/traefik/traefik/security/advisories/GHSA-89p3-4642-cr2w
Restart Required: Yes
Instructions:
1. Download Traefik 3.6.8 from official releases. 2. Stop current Traefik service. 3. Replace binary with patched version. 4. Restart Traefik service. 5. Verify version with 'traefik version' command.
🔧 Temporary Workarounds
Connection timeout reduction
allReduce readTimeout values to limit connection duration
# In Traefik configuration, set lower readTimeout values
# Example: entryPoints.web.readTimeout = "30s"
Network filtering
linuxBlock Postgres SSLRequest packets at network perimeter
# Example iptables rule to block suspicious packets
iptables -A INPUT -p tcp --dport [traefik-port] -m string --string "\x00\x00\x00\x08\x04\xd2\x16\x2f" --algo bm -j DROP
🧯 If You Can't Patch
- Implement rate limiting and connection limits at network level
- Deploy WAF or IPS with DoS protection capabilities
🔍 How to Verify
Check if Vulnerable:
Check Traefik version with 'traefik version' command and compare to 3.6.8Check Version:
traefik versionVerify Fix Applied:
Confirm version is 3.6.8 or higher and test with simulated SSLRequest packets📡 Detection & Monitoring
Log Indicators:
- Unusually high number of long-lived connections
- Connection timeouts exceeding configured limits
- Multiple connections with minimal data transfer
Network Indicators:
- Repeated 8-byte packets to Traefik ports followed by silence
- Abnormal connection duration patterns
SIEM Query:
source="traefik" AND ("readTimeout" OR "connection" duration>300s)