CVE-2026-33603
5.3
MEDIUM
CVSS 3.1
EPSS 0.22%
Description
Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This requires that the attacker is able to position itself between Dovecot and the client connection. If successful, the attacker can eavesdrop communications between Dovecot and client as MITM proxy. Install fixed version. No publicly available exploits are known.
How to fix CVE-2026-33603
To remediate CVE-2026-33603, upgrade the affected package to a fixed version below.
- —upgrade to 1:2.3.13+dfsg1-2+deb11u4 or later
Is CVE-2026-33603 being exploited?
Low — EPSS is 0.2%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 1:2.3.13+dfsg1-2+deb11u4
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |