Improper Control of Resource Identifiers ('Resource Injection') in Dovecot and OX Dovecot Pro - CVE-2026-33603
Published: May 19, 2026
Vulnerability identifier: #VU131867
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-33603
CWE-ID: CWE-99
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vendor: Dovecot
Affected software:
Dovecot
OX Dovecot Pro
Dovecot
OX Dovecot Pro
Detailed vulnerability description
The vulnerability allows a remote attacker to eavesdrop communications between Dovecot and a client.
The vulnerability exists due to improper control of resource identifiers in login when processing a specially crafted base64 exchange between Dovecot and the client. A remote attacker can send a specially crafted base64 exchange to eavesdrop communications between Dovecot and a client.
Exploitation requires the ability to position between Dovecot and the client connection and can be used to fake SCRAM TLS channel binding.
How to mitigate CVE-2026-33603
Install security update from vendor's website.