CVE-2026-27857
Medium · 4.3CVSS
4.3
EPSS
0.8%
Published
Mar 27, 2026
CISA due date
—
The record
Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| openSUSE:Leap 16.0 | dovecot24 | 0 | 2.4.3-160000.1.1 |
| openSUSE:Tumbleweed | dovecot24 | 0 | 2.4.3-1.1 |
Related vulnerabilities
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- CVE-2026-40020 Attacker can use the IMAP SETACL command to inject the anyone permission to user's… Also affects dovecot24
- CVE-2026-33603 Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake… Also affects dovecot24
- CVE-2026-27851 When safe filter is used with variable expansion, all following pipelines on the same… Also affects dovecot24
- CVE-2026-27860 If auth_username_chars is empty, it is possible to inject arbitrary LDAP filter to… Also affects dovecot24
- CVE-2026-27858 Attacker can send a specifically crafted message before authentication that causes… Also affects dovecot24
- CVE-2026-27859 A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use… Also affects dovecot24