CVE-2022-26372
📋 TL;DR
This vulnerability in F5 BIG-IP DNS listeners allows attackers to send specially crafted DNS requests that cause excessive memory consumption, potentially leading to denial of service. Affected systems include BIG-IP versions 11.6.x through 15.1.x with DNS queueing enabled (default configuration).
💻 Affected Systems
- F5 BIG-IP
📦 What is this software?
Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Acceleration Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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Big Ip Application Security Manager by F5
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⚠️ Risk & Real-World Impact
Worst Case
Complete system outage due to memory exhaustion, causing service disruption for all applications hosted on the BIG-IP device.
Likely Case
Degraded performance and intermittent service disruptions as memory resources are consumed by malicious DNS traffic.
If Mitigated
Minimal impact with proper network segmentation and rate limiting on DNS traffic.
🎯 Exploit Status
The vulnerability requires sending undisclosed DNS requests to a vulnerable DNS listener. No authentication is required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 15.1.0.2, 14.1.4.6, 13.1.5
Vendor Advisory: https://support.f5.com/csp/article/K23454411
Restart Required: Yes
Instructions:
1. Download appropriate patch from F5 Downloads. 2. Upload to BIG-IP. 3. Install using tmsh install command. 4. Reboot system after installation.
🔧 Temporary Workarounds
Disable DNS Queueing
allDisable DNS queueing on vulnerable DNS listeners to prevent exploitation
tmsh modify ltm virtual <virtual_server_name> dns-queueing disabled
Implement DNS Rate Limiting
allConfigure rate limiting on DNS traffic to reduce impact
tmsh create ltm profile dns <profile_name> rate-class { ... }
🧯 If You Can't Patch
- Implement network segmentation to restrict access to DNS listeners
- Deploy intrusion prevention systems to detect and block malicious DNS traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check BIG-IP version and verify if DNS listeners with queueing enabled exist: tmsh list ltm virtual one-line | grep -i dnsCheck Version:
tmsh show sys versionVerify Fix Applied:
Verify version is patched: tmsh show sys version | grep -i version📡 Detection & Monitoring
Log Indicators:
- Unusual memory consumption spikes in /var/log/ltm
- Increased DNS query rates in DNS logs
Network Indicators:
- Abnormal DNS traffic patterns to BIG-IP DNS listeners
- High volume of DNS requests from single sources
SIEM Query:
source="bigip_logs" ("memory high" OR "dns queue") | stats count by host