CVE-2023-26433: Open-Xchange Appsuite Backend

Medium severity, CVSS 4.3. EPSS: 1.1% chance of exploitation in the next 30 days.

When adding an external mail account, processing of IMAP "capabilities" responses are not limited to plausible sizes. Attacker with access to a rogue IMAP service could trigger requests that lead to excessive resource usage and eventually service unavailability. We now limit accepted IMAP server response to reasonable length/size. No publicly available exploits are known.

Affected products

• Open-Xchange Open-Xchange Appsuite Backend: before 7.10.6 (fixed in 7.10.6); from 8.0.0, before 8.11.0 (fixed in 8.11.0); version 7.10.6 only

Published 2023-06-20. Last modified 2026-06-17.