CVE-2021-39160
📋 TL;DR
CVE-2021-39160 is a critical vulnerability in nbgitpuller, a Jupyter server extension for syncing git repositories. Due to unsanitized input in crafted links, attackers can execute arbitrary code in the user's environment. All users of nbgitpuller versions before 0.10.2 are affected.
💻 Affected Systems
- nbgitpuller
📦 What is this software?
Nbgitpuller by Jupyterhub
⚠️ Risk & Real-World Impact
Worst Case
Full compromise of the Jupyter environment allowing attackers to execute arbitrary commands, access sensitive data, and potentially pivot to other systems.
Likely Case
Remote code execution leading to data theft, unauthorized access to Jupyter notebooks, and potential lateral movement within the environment.
If Mitigated
Limited impact if proper network segmentation and access controls prevent exploitation attempts.
🎯 Exploit Status
Exploitation requires users to click malicious links. The advisory includes technical details that could be used to create exploits.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.10.2
Vendor Advisory: https://github.com/jupyterhub/nbgitpuller/security/advisories/GHSA-mq5p-2mcr-m52j
Restart Required: Yes
Instructions:
1. Stop Jupyter server. 2. Run: pip install --upgrade nbgitpuller==0.10.2. 3. Restart Jupyter server. 4. Verify the fix by checking the version.
🔧 Temporary Workarounds
Disable nbgitpuller extension
allTemporarily disable the nbgitpuller extension until patching is possible
jupyter serverextension disable nbgitpuller
🧯 If You Can't Patch
- Implement strict network controls to prevent access to Jupyter servers from untrusted networks
- Educate users about the risks of clicking unknown links in the Jupyter environment
🔍 How to Verify
Check if Vulnerable:
Check nbgitpuller version: pip show nbgitpuller | grep VersionCheck Version:
pip show nbgitpuller | grep VersionVerify Fix Applied:
Verify version is 0.10.2 or higher: pip show nbgitpuller | grep Version📡 Detection & Monitoring
Log Indicators:
- Unusual git operations via nbgitpuller
- Suspicious URL parameters in Jupyter access logs
- Unexpected process execution from Jupyter context
Network Indicators:
- Unusual outbound connections from Jupyter servers
- Git operations to unknown repositories
SIEM Query:
source="jupyter" AND (url="*nbgitpuller*" AND url="*;*" OR url="*|*" OR url="*`*" OR url="*$(*")🔗 References
- https://github.com/jupyterhub/nbgitpuller/blob/main/CHANGELOG.md#0102---2021-08-25
- https://github.com/jupyterhub/nbgitpuller/commit/07690644f29a566011dd0d7ba14cae3eb0490481
- https://github.com/jupyterhub/nbgitpuller/security/advisories/GHSA-mq5p-2mcr-m52j
- https://github.com/jupyterhub/nbgitpuller/blob/main/CHANGELOG.md#0102---2021-08-25
- https://github.com/jupyterhub/nbgitpuller/commit/07690644f29a566011dd0d7ba14cae3eb0490481
- https://github.com/jupyterhub/nbgitpuller/security/advisories/GHSA-mq5p-2mcr-m52j
