CVE-2026-27857 Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage
Description
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 products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| OX Dovecot Pro 2.3 | earliest → 2.3.0 | No fix stated |
| Red Hat Enterprise Linux Server (v. 7 ELS) | Versions not published | |
| Red Hat Enterprise Linux Server Optional (v. 7 ELS) | Versions not published | |
| Red Hat Enterprise Linux AppStream EUS (v. 10.0) | Versions not published | |
| Red Hat Enterprise Linux AppStream (v. 10) | Versions not published | |
| Red Hat Enterprise Linux AppStream (v. 8) | Versions not published | |
| Red Hat Enterprise Linux AppStream AUS (v.8.4) | Versions not published | |
| Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) | Versions not published | |
| Red Hat Enterprise Linux AppStream AUS (v.8.6) | Versions not published |
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References
- documentation.open-xchange.com documentation.open-xchange.com
Timeline
- Published
- Last modified