Description
When sending invalid base64 SASL data, login process is disconnected from the auth server, causing all active authentication sessions to fail. Invalid BASE64 data can be used to DoS a vulnerable server to break concurrent logins. Install fixed version or disable concurrency in login processes (heavy perfomance penalty on large deployments). No publicly available exploits are known.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Open-Xchange | OX Dovecot Pro | ≤ 3.1.0, ≤ 2.4.0 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | dovecot | 1:2.4.3+dfsg1-1 | — |
| Debian 13 | dovecot | 1:2.4.1+dfsg1-6+deb13u4 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | dovecot | 1:2.4.1+dfsg1-5ubuntu4.1 | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 15 SP6 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 15 SP5 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 15 SP4 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | dovecot24 | 2.4.3-160000.1.1 | SUSE-SU-2026:21208-1 |
| SLES for SAP 15 SP6 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES for SAP 15 SP5 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES for SAP 15 SP4 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 16.0 | dovecot24 | 2.4.3-160000.1.1 | SUSE-SU-2026:21208-1 |
| SLE HPC 15 SP5 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLE HPC 15 SP4 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | dovecot24 | 2.4.3-1.1 | openSUSE-SU-2026:10442-1 |
| openSUSE Leap 16.0 | dovecot24 | 2.4.3-160000.1.1 | openSUSE-SU-2026:20554-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | dovecot | 2.4.3-r0 | — |
| Alpine v3.23 | dovecot | 2.4.3-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | dovecot | No fix yet | — |
Advisories 5
- SUSE-SU-2026:4139-1 Security update for dovecot23 SUSE / openSUSE Security Updates · Sep 28, 2026
- WID-SEC-2026-0891 Dovecot: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 16, 2026
- openSUSE-SU-2026:20554-1 Security update for dovecot24 SUSE / openSUSE Security Updates · Apr 22, 2026
- SUSE-SU-2026:21208-1 Security update for dovecot24 SUSE / openSUSE Security Updates · Apr 22, 2026
- openSUSE-SU-2026:10442-1 dovecot24-2.4.3-1.1 on GA media SUSE / openSUSE Security Updates · Mar 28, 2026