CVE-2025-40778
📋 TL;DR
This CVE describes a DNS cache poisoning vulnerability in BIND where the server accepts records too leniently from answers, allowing attackers to inject forged data into DNS caches. This affects BIND 9 versions across multiple release streams. Organizations running vulnerable BIND versions as DNS servers are at risk.
💻 Affected Systems
- ISC BIND 9
⚠️ 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
Complete DNS cache poisoning leading to traffic redirection to malicious sites, credential theft, malware distribution, and service disruption across entire DNS infrastructure.
Likely Case
Targeted DNS spoofing attacks redirecting users to phishing sites or intercepting sensitive communications for specific domains.
If Mitigated
Limited impact with proper network segmentation, DNSSEC validation, and monitoring in place, though some risk remains until patched.
🎯 Exploit Status
Exploitation requires network access to the DNS server and knowledge of DNS protocol specifics.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.16.51, 9.18.40, 9.20.14, 9.21.13, and corresponding S1 versions
Vendor Advisory: https://kb.isc.org/docs/cve-2025-40778
Restart Required: Yes
Instructions:
1. Download patched version from ISC website. 2. Stop BIND service. 3. Install updated package. 4. Restart BIND service. 5. Verify version and functionality.
🔧 Temporary Workarounds
Restrict Recursive Queries
allLimit recursive queries to trusted clients only to reduce attack surface
# In named.conf, add: acl trusted-clients { 192.168.1.0/24; };
# Then in options: allow-recursion { trusted-clients; };
Enable DNSSEC Validation
allForce DNSSEC validation to detect forged responses
# In named.conf options: dnssec-validation auto;
🧯 If You Can't Patch
- Implement strict network ACLs to limit DNS traffic to trusted sources only
- Deploy DNS monitoring and anomaly detection to identify cache poisoning attempts
🔍 How to Verify
Check if Vulnerable:
Run: named -v and check if version falls in affected rangesCheck Version:
named -vVerify Fix Applied:
Run: named -v and confirm version is 9.16.51+, 9.18.40+, 9.20.14+, or 9.21.13+📡 Detection & Monitoring
Log Indicators:
- Unexpected DNS response patterns
- Multiple failed DNSSEC validations
- Unusual query sources
Network Indicators:
- DNS responses with mismatched transaction IDs
- Suspicious TTL values
- Unexpected record types in responses
SIEM Query:
source="bind" AND (event="dnssec-failure" OR event="cache-poisoning")