CVE-2021-3770
📋 TL;DR
CVE-2021-3770 is a heap-based buffer overflow vulnerability in Vim text editor that allows attackers to execute arbitrary code by tricking users into opening specially crafted files. This affects all users who open untrusted files with vulnerable Vim versions. The vulnerability occurs during file processing when Vim incorrectly handles certain data structures.
💻 Affected Systems
- Vim
📦 What is this software?
Fedora by Fedoraproject
Fedora by Fedoraproject
Fedora by Fedoraproject
Ontap Select Deploy Administration Utility by Netapp
View all CVEs affecting Ontap Select Deploy Administration Utility →
Vim by Vim
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the Vim user, potentially leading to full system compromise if Vim is run with elevated privileges.
Likely Case
Local privilege escalation or arbitrary code execution when users open malicious files, potentially leading to data theft or further system compromise.
If Mitigated
Limited impact if Vim runs with minimal privileges and users only open trusted files, though the vulnerability still exists.
🎯 Exploit Status
Exploitation requires user interaction (opening a malicious file). Proof-of-concept code is available in public repositories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Vim 8.2.3489 and later
Vendor Advisory: https://github.com/vim/vim/commit/b7081e135a16091c93f6f5f7525a5c58fb7ca9f9
Restart Required: No
Instructions:
1. Update Vim using your system's package manager. 2. For Linux: 'sudo apt update && sudo apt upgrade vim' (Debian/Ubuntu) or 'sudo yum update vim' (RHEL/CentOS). 3. For macOS: 'brew upgrade vim'. 4. For Windows: Download latest version from vim.org. 5. Verify update with 'vim --version'.
🔧 Temporary Workarounds
Restrict file access
allLimit Vim usage to trusted files only and avoid opening files from untrusted sources.
Use alternative editor
allTemporarily use a different text editor (nano, emacs, etc.) until Vim is patched.
🧯 If You Can't Patch
- Run Vim with minimal privileges (non-root user)
- Implement application whitelisting to restrict Vim execution to specific trusted directories
🔍 How to Verify
Check if Vulnerable:
Run 'vim --version' and check if version is below 8.2.3489Check Version:
vim --version | head -1Verify Fix Applied:
Run 'vim --version' and confirm version is 8.2.3489 or higher📡 Detection & Monitoring
Log Indicators:
- Vim crashes with segmentation faults
- Unusual process spawning from Vim sessions
- Abnormal memory usage patterns in Vim processes
Network Indicators:
- File downloads followed by immediate Vim execution
- Suspicious file transfers to systems running Vim
SIEM Query:
process_name:vim AND (event_type:crash OR memory_usage:>threshold)🔗 References
- http://www.openwall.com/lists/oss-security/2021/10/01/1
- https://github.com/vim/vim/commit/b7081e135a16091c93f6f5f7525a5c58fb7ca9f9
- https://huntr.dev/bounties/016ad2f2-07c1-4d14-a8ce-6eed10729365
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J2CJLY3CF55I2ULG2X4ENXLSXAXYW5J4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X4FFQARG3LGREPDZRI4C7ERQL3RJKEWQ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZFNTMVZCN4TRTTCAXRLVQ7H2P7FYAIZQ/
- https://security.gentoo.org/glsa/202208-32
- https://security.netapp.com/advisory/ntap-20221124-0003/
- http://www.openwall.com/lists/oss-security/2021/10/01/1
- https://github.com/vim/vim/commit/b7081e135a16091c93f6f5f7525a5c58fb7ca9f9
- https://huntr.dev/bounties/016ad2f2-07c1-4d14-a8ce-6eed10729365
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/J2CJLY3CF55I2ULG2X4ENXLSXAXYW5J4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/X4FFQARG3LGREPDZRI4C7ERQL3RJKEWQ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZFNTMVZCN4TRTTCAXRLVQ7H2P7FYAIZQ/
- https://security.gentoo.org/glsa/202208-32
- https://security.netapp.com/advisory/ntap-20221124-0003/
