CVE-2025-62820
📋 TL;DR
Slack Nebula versions before 1.9.7 incorrectly handle CIDR configurations, allowing arbitrary source IP addresses to be accepted within the Nebula network. This affects organizations using Nebula for mesh VPN networking with vulnerable configurations.
💻 Affected Systems
- Slack Nebula
⚠️ 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
An attacker could bypass Nebula's IP filtering and gain unauthorized access to internal network resources, potentially leading to lateral movement and data exfiltration.
Likely Case
Misconfigured Nebula installations could allow unintended devices to join the mesh network, creating unauthorized network access points.
If Mitigated
With proper network segmentation and monitoring, impact would be limited to potential unauthorized access within the Nebula mesh only.
🎯 Exploit Status
Exploitation requires knowledge of Nebula network configuration and ability to craft packets with specific source IPs.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.9.7
Vendor Advisory: https://github.com/slackhq/nebula/pull/1493
Restart Required: Yes
Instructions:
1. Download Nebula 1.9.7 or later from GitHub releases. 2. Replace existing Nebula binary with new version. 3. Restart Nebula service on all nodes.
🔧 Temporary Workarounds
Restrict Nebula network access
allImplement additional network-level controls to restrict access to Nebula mesh endpoints
🧯 If You Can't Patch
- Implement strict network segmentation around Nebula endpoints
- Enable detailed logging and monitoring for Nebula network traffic
🔍 How to Verify
Check if Vulnerable:
Check Nebula version using 'nebula -version' command; if version is below 1.9.7, system is vulnerable if using CIDR filtering.Check Version:
nebula -versionVerify Fix Applied:
After patching, verify version is 1.9.7 or higher and test CIDR filtering functionality.📡 Detection & Monitoring
Log Indicators:
- Unexpected IP addresses connecting to Nebula network
- Failed authentication attempts from unexpected sources
Network Indicators:
- Unusual traffic patterns within Nebula mesh
- Connections from IPs outside configured CIDR ranges
SIEM Query:
source="nebula" AND (event="connection" OR event="auth") AND NOT src_ip IN [allowed_cidr_ranges]