CVE-2026-27857
Publication date 27 March 2026
Last updated 31 March 2026
Ubuntu priority
Description
imap-login: Excessive memory usage DoS. 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. No publicly available exploits are known.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| dovecot | 25.10 questing |
Fixed 1:2.4.1+dfsg1-5ubuntu4.1
|
| 24.04 LTS noble |
Fixed 1:2.3.21+dfsg1-2ubuntu6.3
|
|
| 22.04 LTS jammy |
Fixed 1:2.3.16+dfsg1-3ubuntu2.7
|
|
| 20.04 LTS focal |
Vulnerable
|
|
| 18.04 LTS bionic |
Not affected
|
|
| 16.04 LTS xenial |
Not affected
|
|
| 14.04 LTS trusty |
Not affected
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
4.3 · Medium
|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | None |
| Availability impact | Low |
| Vector | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L |
References
Related Ubuntu Security Notices (USN)
- USN-8136-1
- Dovecot vulnerabilities
- 31 March 2026