HOMEVULNERABILITIESCVE-2021-3181
MEDIUM

CVE-2021-3181

CWE-401Published: January 19, 2021· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-3181 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected Vendors & Products

Debian1 product(s)
debian linux
Fedora1 product(s)
fedora
mutt1 product(s)
mutt
Source: NVD CPE · 5 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://gitlab.com/muttmua/mutt/-/commit/4a2becbdb4422aaffe3ce314991b9d670b7adf17
PATCHhttps://gitlab.com/muttmua/mutt/-/commit/939b02b33ae29bc0d642570c1dcfd4b339037d19
PATCHhttps://gitlab.com/muttmua/mutt/-/commit/d4305208955c5cdd9fe96dfa61e7c1e14e176a14
PATCHhttps://gitlab.com/muttmua/mutt/-/commit/4a2becbdb4422aaffe3ce314991b9d670b7adf17
PATCHhttps://gitlab.com/muttmua/mutt/-/commit/939b02b33ae29bc0d642570c1dcfd4b339037d19
PATCHhttps://gitlab.com/muttmua/mutt/-/commit/d4305208955c5cdd9fe96dfa61e7c1e14e176a14
ADVISORYhttp://www.openwall.com/lists/oss-security/2021/01/19/10
ADVISORYhttp://www.openwall.com/lists/oss-security/2021/01/27/3
ADVISORYhttps://gitlab.com/muttmua/mutt/-/issues/323
ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/01/msg00017.html
ADVISORYhttps://security.gentoo.org/glsa/202101-25
ADVISORYhttps://www.debian.org/security/2021/dsa-4838
ADVISORYhttp://www.openwall.com/lists/oss-security/2021/01/19/10
ADVISORYhttp://www.openwall.com/lists/oss-security/2021/01/27/3
ADVISORYhttps://gitlab.com/muttmua/mutt/-/issues/323
ADVISORYhttps://lists.debian.org/debian-lts-announce/2021/01/msg00017.html
ADVISORYhttps://security.gentoo.org/glsa/202101-25
ADVISORYhttps://www.debian.org/security/2021/dsa-4838

All References (22)

→
http://www.openwall.com/lists/oss-security/2021/01/19/10Mailing List · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2021/01/27/3Mailing List · Third Party Advisory
→
https://gitlab.com/muttmua/mutt/-/commit/4a2becbdb4422aaffe3ce314991b9d670b7adf17Patch · Third Party Advisory
→
https://gitlab.com/muttmua/mutt/-/commit/939b02b33ae29bc0d642570c1dcfd4b339037d19Patch · Third Party Advisory
→
https://gitlab.com/muttmua/mutt/-/commit/d4305208955c5cdd9fe96dfa61e7c1e14e176a14Patch · Third Party Advisory
→
https://gitlab.com/muttmua/mutt/-/issues/323Third Party Advisory
→
https://lists.debian.org/debian-lts-announce/2021/01/msg00017.htmlMailing List · Third Party Advisory
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DXGWXFO77HBCD3VYEIYHHYU33LYWWWNQ/
→
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/P2OMLQKAOHPYQA4GI7ZUO6UKCPUHLYO7/
→
https://security.gentoo.org/glsa/202101-25Third Party Advisory
→
https://www.debian.org/security/2021/dsa-4838Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2021/01/19/10Mailing List · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2021/01/27/3Mailing List · Third Party Advisory
→
https://gitlab.com/muttmua/mutt/-/commit/4a2becbdb4422aaffe3ce314991b9d670b7adf17Patch · Third Party Advisory
→
https://gitlab.com/muttmua/mutt/-/commit/939b02b33ae29bc0d642570c1dcfd4b339037d19Patch · Third Party Advisory

Quick Facts

CVE IDCVE-2021-3181
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessCWE-401
CISA KEVNo
Affected3 vendor(s)
PublishedJan 19, 2021

Related CVEs (CWE-401)

CVE-2023-33718
8.8
CVE-2021-40633
8.8
CVE-2019-17340
8.8
CVE-2019-6128
8.8
CVE-2026-0646
8.7
CVE-2021-1387
8.6

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-3181 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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