Low · published September 10, 2026
An issue was discovered in Cyrus IMAP before 3.12.4. A JMAP email-header blob ID can reference an out-of-bounds index. An authenticated user could attempt to download a crafted JMAP blob ID of the form H<emailid>-<index>, which could read past the end of the internal blob_headers array during download, exposing adjacent heap memory.
| Product | Versions | Fixed in |
|---|---|---|
| cyrus/imap | < 3.8.8 | 3.8.8 |
| cyrus/imap | ≥ 3.9.0, < 3.10.4 | 3.10.4 |
| cyrus/imap | ≥ 3.11.0, < 3.12.4 | 3.12.4 |