| Name | CVE-2025-59028 |
| 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| dovecot (PTS) | bullseye | 1:2.3.13+dfsg1-2+deb11u1 | fixed |
| bullseye (security) | 1:2.3.13+dfsg1-2+deb11u2 | fixed | |
| bookworm, bookworm (security) | 1:2.3.19.1+dfsg1-2.1+deb12u1 | fixed | |
| trixie | 1:2.4.1+dfsg1-6+deb13u3 | vulnerable | |
| trixie (security) | 1:2.4.1+dfsg1-6+deb13u1 | vulnerable | |
| forky, sid | 1:2.4.2+dfsg1-4 | vulnerable |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| dovecot | source | bullseye | (not affected) | |||
| dovecot | source | bookworm | (not affected) | |||
| dovecot | source | (unstable) | (unfixed) |
[bookworm] - dovecot <not-affected> (Vulnerable code introduced later)
[bullseye] - dovecot <not-affected> (Vulnerable code introduced later)
https://dovecot.org/mailman3/archives/list/dovecot-news@dovecot.org/thread/IKIHZX77IPTGSP5WBIPJUOFBUQFKVPE7/
https://documentation.open-xchange.com/dovecot/security/advisories/html/2026/oxdc-adv-2026-0001.html#cve-2025-59028-invalid-base64-authentication-can-cause-dos-for-other-logins
Introduced with: https://github.com/dovecot/core/commit/1486c30e191ff079bfa78e7950173bb33d8073d9 (2.4.1)
Fixed by: https://github.com/dovecot/core/commit/56df8acb5f21abaa039f91f1b0839a75719231de (2.4.3)