How severe is CVE-2021-3181?

CVE-2021-3181 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-3181 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3181?

CVE-2021-3181 primarily affects Mutt. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-3181?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-3181 published?

CVE-2021-3181 was published on 2021-01-19 and last updated on 2026-06-17.

CVE-2021-3181

CVE-2021-3181 is a medium-severity vulnerability in Mutt with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-401.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 3% (85th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-401
Affected product: Mutt
Published: 2021-01-19
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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 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.
How severe is CVE-2021-3181?: CVE-2021-3181 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-3181 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (85th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3181?: CVE-2021-3181 primarily affects Mutt. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-3181?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3181 published?: CVE-2021-3181 was published on 2021-01-19 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:mutt:mutt:*:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

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