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CVE-2026-27857

medium CVSS 4.3 EPSS 0.7%

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.

Versions it affects

Software versions checked with the free lookup that CVE-2026-27857 applies to, and the release that fixes it where the sources name one.

Dovecot 2.2.36

At a glance

Severity
Medium
CVSS base score
4.3 out of 10
Known exploited
Not in CISA's catalogue of exploited vulnerabilities
EPSS
0.7% probability of exploitation in the next 30 days, higher than 50% of scored vulnerabilities
Weakness
CWE-400
Published
2026-03-27
NVD CVE.org Advisory record

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