Home/CVE/Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This
CVE

CVE-2026-33603

Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding. This

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.

MEDIUM · CVSS 6.8 EPSS 9e-05
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  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0

Affected Products & Versions

2

Scoring & Timeline

6.8
MEDIUM · CVSS v3.1 · security@open-xchange.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD12 May 2026 · 02:17 PM
CVSS VectorCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.

Vendor Advisories

2
suse-csafopenSUSE-SU-2026:10766-1
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
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