CVE & CISA-KEV Catalog

CVE-2026-33603

MEDIUM
6.8
CVSS v3
NVD

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.

CWE-99

How to fix

Remediation Available
dovecotDebian
Fixed in:1:2.3.13+dfsg1-2+deb11u4CVE-2026-33603
Fixed in:1:2.3.19.1+dfsg1-2.1+deb12u6CVE-2026-33603
Fixed in:1:2.4.1+dfsg1-6+deb13u6CVE-2026-33603
Fixed in:1:2.4.4+dfsg1-1CVE-2026-33603
dovecotUbuntu
Fixed in:1:2.3.16+dfsg1-3ubuntu2.9USN-8365-1
Fixed in:1:2.3.21+dfsg1-2ubuntu6.5USN-8365-1
Fixed in:1:2.4.1+dfsg1-5ubuntu4.2USN-8365-1
dovecot-coreUbuntu
Fixed in:1:2.3.16+dfsg1-3ubuntu2.9USN-8365-1
Fixed in:1:2.3.21+dfsg1-2ubuntu6.5USN-8365-1
Fixed in:1:2.4.1+dfsg1-5ubuntu4.2USN-8365-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorAdjacent
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityNone

CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploit Intelligence

0.22%probability of exploitation in 30 days
13thpercentile

Low risk: more likely to be exploited than 13% of all known CVEs.

References

Embed a live status badge for CVE-2026-33603
CVE-2026-33603 severity badge

Markdown

[![CVE-2026-33603](https://tridentstack.com/cve/badge/CVE-2026-33603.svg)](https://tridentstack.com/cve/CVE-2026-33603)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-33603"><img src="https://tridentstack.com/cve/badge/CVE-2026-33603.svg" alt="CVE-2026-33603"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-18.