CVE-2021-3778
📋 TL;DR
CVE-2021-3778 is a heap-based buffer overflow vulnerability in Vim text editor that could allow attackers to execute arbitrary code or cause denial of service. The vulnerability affects users who open specially crafted files with vulnerable Vim versions. This impacts both interactive users and automated systems using Vim for file processing.
💻 Affected Systems
- Vim
- Neovim (potentially)
- Applications embedding Vim libraries
📦 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 process, potentially leading to full system compromise if Vim runs with elevated privileges.
Likely Case
Application crash (denial of service) when processing malicious files, with potential for limited code execution in specific configurations.
If Mitigated
Application crash with no code execution if exploit fails or security controls like ASLR/PIE are effective.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious file. Proof-of-concept code is available in public references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Vim 8.2.3489 and later
Vendor Advisory: https://github.com/vim/vim/commit/65b605665997fad54ef39a93199e305af2fe4d7f
Restart Required: No
Instructions:
1. Update Vim using your system package manager. 2. For Debian/Ubuntu: sudo apt update && sudo apt upgrade vim. 3. For RHEL/CentOS: sudo yum update vim-enhanced. 4. For macOS: brew upgrade vim. 5. For Windows: Download latest version from vim.org.
🔧 Temporary Workarounds
Disable vulnerable features
allAvoid opening untrusted files with Vim and use alternative text editors for unknown files.
Use sandboxed environment
linuxRun Vim in containerized or sandboxed environments when processing untrusted files.
docker run --rm -it vim:latest
🧯 If You Can't Patch
- Restrict Vim usage to trusted files only and implement application allowlisting
- Implement network segmentation to limit potential lateral movement if exploitation occurs
🔍 How to Verify
Check if Vulnerable:
Check Vim version with 'vim --version' and compare to vulnerable range (before 8.2.3489).Check Version:
vim --version | grep 'VIM - Vi IMproved'Verify Fix Applied:
Verify version is 8.2.3489 or later with 'vim --version | head -1'.📡 Detection & Monitoring
Log Indicators:
- Vim process crashes with segmentation faults
- Abnormal termination of Vim processes in system logs
Network Indicators:
- Unusual outbound connections from systems where Vim was recently used
SIEM Query:
Process:Name=vim AND EventID=1000 (Application Error) OR Process:Name=vim AND EventID=1001 (Application Hang)🔗 References
- http://www.openwall.com/lists/oss-security/2021/10/01/1
- https://github.com/vim/vim/commit/65b605665997fad54ef39a93199e305af2fe4d7f
- https://huntr.dev/bounties/d9c17308-2c99-4f9f-a706-f7f72c24c273
- https://lists.debian.org/debian-lts-announce/2022/01/msg00003.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7K4JJBIH3OQSZRVTWKCJCDLGMFGQ5DOH/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/S42L4Z4DTW4LHLQ4FJ33VEOXRCBE7WN4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TE62UMYBZE4AE53K6OBBWK32XQ7544QM/
- https://security.gentoo.org/glsa/202208-32
- https://security.netapp.com/advisory/ntap-20221118-0003/
- http://www.openwall.com/lists/oss-security/2021/10/01/1
- https://github.com/vim/vim/commit/65b605665997fad54ef39a93199e305af2fe4d7f
- https://huntr.dev/bounties/d9c17308-2c99-4f9f-a706-f7f72c24c273
- https://lists.debian.org/debian-lts-announce/2022/01/msg00003.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/7K4JJBIH3OQSZRVTWKCJCDLGMFGQ5DOH/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/S42L4Z4DTW4LHLQ4FJ33VEOXRCBE7WN4/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TE62UMYBZE4AE53K6OBBWK32XQ7544QM/
- https://security.gentoo.org/glsa/202208-32
- https://security.netapp.com/advisory/ntap-20221118-0003/
