CVE-2026-42006
MediumCVSS 4.3Exploitation Probability (EPSS)
Low risk46th percentile - higher than 46% of all known CVEs
Summary
An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open – using open braces to bypass the limit. Excessive bracing can cause memory usage up to the configured memory limit.
Risk Assessment
The organization risks memory exhaustion on the IMAP server, potentially leading to denial of service (DoS) and disruption of email communication.
Recommendation
Install the patched version or configure vsz_limit for the IMAP process to a low value.
Other vulnerabilities in IMAP server
Original NVD description (English source)
An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.