CVE-2021-3181 Denial of service in n/a

What is CVE-2021-3181?

CVE-2021-3181 is a medium-severity denial of service vulnerability in Debian Debian Linux, published on 19 Jan 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

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.

Weakness: CWE-401

Which versions are affected by CVE-2021-3181?

It affects 3 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Mutt Mutt.

How do I fix CVE-2021-3181?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-3181 being exploited?

There is no known exploitation of CVE-2021-3181 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-3181, DLA-2529-1, DSA-4838-1, GHSA-prp6-7gc9-4jmw, MGASA-2021-0070, OESA-2021-1079 and 6 more.