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Fencer Intel
medium 6.5

CVE-2021-3181 json

rfc822.c in Mutt through 2.0.4 allows remote attackers to cause a denial of service (mailbox unavailability) by sending email messages with…

published 5y ago modified 4mo ago also EUVD-2021-26524

cvss
6.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.8%
EPSS 2.8% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

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.

Patch / fix

  • mutt Debian 14, Debian 13, Debian 12 2.0.5-1

debian advisories DEBIAN-CVE-2021-3181

  • mutt Ubuntu 16.04 LTS 1.5.24-1ubuntu0.6
  • mutt Ubuntu 18.04 LTS 1.9.4-3ubuntu0.5
  • mutt Ubuntu 20.04 LTS 1.13.2-1ubuntu0.4

ubuntu advisories UBUNTU-CVE-2021-3181

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • mutt RHEL 8 5:2.0.7-1.el8

red hat advisories RHSA-2021:4181

  • mutt SLES for SAP 12 SP5, SLES 12 SP5 1.10.1-55.24.1
  • mutt SLE Module for Basesystem 15 SP2 1.10.1-3.20.1

suse advisories SUSE-SU-2021:0196-1SUSE-SU-2021:0195-1

  • mutt openSUSE Tumbleweed 2.0.7-2.2
  • mutt openSUSE Leap 15.2 1.10.1-lp152.3.15.1
  • mutt openSUSE Leap 15.1 1.10.1-lp151.2.15.1

opensuse advisories openSUSE-SU-2024:11069-1openSUSE-SU-2021:0162-1openSUSE-SU-2021:0161-1

  • mutt AlmaLinux 8 5:2.0.7-1.el8

almalinux advisories ALSA-2021:4181

  • mutt Rocky Linux 8 5:2.0.7-1.el8

rocky linux advisories RLSA-2021:4181

  • mutt Alpine 3.12 1.14.7-r0
  • mutt Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 2.0.4-r1

alpine advisories ALPINE-CVE-2021-3181

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • mutt Arch Linux 2.0.5-1

arch linux advisories AVG-1476

Is CVE-2021-3181 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-3181 updated cvss 6.5

mutt: Memory leak when parsing rfc822 group addresses

  • Red Hat Enterprise Linux 6 mutt Red Hat Enterprise Linux 7 mutt
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) mutt 2.0.7-1.el8
    fixed: vendor fix RHSA-2021:4181
  • Red Hat Enterprise Linux 9 mutt
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.83% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.