CVE-2026-27857
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk48th percentile - higher than 48% of all known CVEs
Summary
Sending a "NOOP (((...)))" command with 4000 parentheses increases memory usage by about 1 MB. Longer commands cause client disconnection. An attacker can keep this memory allocated by not sending the line feed (LF) character.
Risk Assessment
An attacker from a single IP can create 1000 connections, allocating 1 GB of memory, potentially exceeding the VSZ limit and killing the process along with its other proxied connections.
Recommendation
Install the fixed version. No other remediation is available.
Original NVD description (English source)
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.