What is CVE-2026-33603?

CVE-2026-33603 is a medium-severity vulnerability in Dovecot, classified under Resource Injection. CVSS score: 6.8/10. Published 2026-05-12.

How severe is CVE-2026-33603?

Medium severity. CVSS v3 base score is 6.8 out of 10.

Vulnerability in Dovecot

CVE-2026-33603

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 att…

EPSS: 0.000 (1.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Dovecot
Open-xchange Dovecot
Open-xchange Gmbh Ox Dovecot Pro — versions 0

Weakness classification (CWE)

CWE-99 — Resource Injection

References

security@open-xchange.com (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-33603?: CVE-2026-33603 is a medium-severity vulnerability in Dovecot, classified under Resource Injection. CVSS score: 6.8/10. Published 2026-05-12.
How severe is CVE-2026-33603?: Medium severity. CVSS v3 base score is 6.8 out of 10.