CyberSecBulletin
CVE-2026-73208NVD status: Deferred

OX Dovecot Pro: Improper Authentication

Published Updated By the CyberSecBulletin desk

CVE-2026-73208 is a high-severity improper authentication vulnerability in OX Dovecot Pro from Open-Xchange, with a CVSS 3.1 base score of 7.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 2.3.22.2, 3.0.7, 3.1.6 as the first without the flaw, so updating OX Dovecot Pro to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.31% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update OX Dovecot Pro to 2.3.22.2 or 3.0.7 or 3.1.6, whichever matches your release line, or a later version.
  2. Update OX Dovecot CE to 2.4.5 or a later version.
  3. Read the advisory on documentation.open-xchange.com for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Open-XchangeOX Dovecot Pro2.3.13 up to, but not including, 2.3.22.2; 3.0.0 up to, but not including, 3.0.7; 3.1.0 up to, but not including, 3.1.62.3.22.2, 3.0.7, 3.1.6
Open-XchangeOX Dovecot CE2.3.13 up to, but not including, 2.4.52.4.5

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by CNA (open-xchange.com).

Official description

An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2 token response does not contain a scope claim, the audience claim is used in its place and checked against the configured required scopes. These are different concepts, and the audience claim does not describe what a token is allowed to do. A token that grants no relevant permissions can be accepted because its intended recipient value happens to match a configured scope name, granting access that should have been denied. It also hides an identity provider misconfiguration where scopes are not being issued at all. Ensure the identity provider issues a scope claim for all tokens used with Dovecot, and that configured scope names do not match audience values. Update to non-vulnerable version. No publicly available exploits are known.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Authentication

When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.

How developers prevent this class of flaw

  • Use an authentication framework or library such as the OWASP ESAPI Authentication feature.

More Improper Authentication vulnerabilities (CWE-287)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in OX Dovecot Pro

All OX Dovecot Pro vulnerabilities

Recent Improper Authentication vulnerabilities

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