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Vulnerability record · CVE-2021-33582 · published 1 September 2021

CVE-2021-33582: Cyrus imap vulnerability

Cyrus · Imap

Cyrus IMAP before 3.4.2 allows remote attackers to cause a denial of service (multiple-minute daemon hang) via input that is mishandled during hash-table interaction. Because there are many insertions into a single bucket, strcmp becomes slow. This is fixed in 3.4.2, 3.2.8, and 3.0.16.

7.5 CVSS 3.1 High EPSS 3.1% · top 12.8% CWE-407 · CWE-407
7.5CVSS 3.1 base score, v2 5.0
3.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
14References
17 Jun 2026Last modified by NVD

Description

Cyrus IMAP before 3.4.2 allows remote attackers to cause a denial of service (multiple-minute daemon hang) via input that is mishandled during hash-table interaction. Because there are many insertions into a single bucket, strcmp becomes slow. This is fixed in 3.4.2, 3.2.8, and 3.0.16.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://cyrus.topicbox.com/groups/announce/T3dde0a2352462975-M1386fc44adf967e072f8df13/cyrus-imap-3-4-2-3-2-8-and-3-0-16 PatchVendor Advisory
https://github.com/cyrusimap/cyrus-imapd/commits/master PatchThird Party Advisory
https://github.com/cyrusimap/cyrus-imapd/security/advisories Not ApplicableThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/06/msg00013.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6HEO3RURJW6NLIXS7NK5PVU
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WJZB45QBUN7CZFGOWCZYUYA
https://www.cyrusimap.org/imap/download/release-notes/index.html PatchRelease NotesVendor Advisory
https://cyrus.topicbox.com/groups/announce/T3dde0a2352462975-M1386fc44adf967e072f8df13/cyrus-imap-3-4-2-3-2-8-and-3-0-16 PatchVendor Advisory
https://github.com/cyrusimap/cyrus-imapd/commits/master PatchThird Party Advisory
https://github.com/cyrusimap/cyrus-imapd/security/advisories Not ApplicableThird Party Advisory
https://lists.debian.org/debian-lts-announce/2022/06/msg00013.html Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6HEO3RURJW6NLIXS7NK5PVU
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WJZB45QBUN7CZFGOWCZYUYA
https://www.cyrusimap.org/imap/download/release-notes/index.html PatchRelease NotesVendor Advisory

Track CVE-2021-33582 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

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Source: NIST National Vulnerability Database (record CVE-2021-33582), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.