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CVE PROGRAM SOURCE RECORD3.7 Low

CVE-2026-40203

When IMAP compression is enabled, the same compression state is reused across responses in a session, so response sizes depend on both attacker-supplied mail and other mail in the

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Status
Published
Published
Updated
Assigning organization
OX

Description

When IMAP compression is enabled, the same compression state is reused across responses in a session, so response sizes depend on both attacker-supplied mail and other mail in the same mailbox. An attacker that can send mail to a user and can also observe the sizes of that user's IMAP traffic can confirm whether the body of a small message matches a guessed text. Recovery of arbitrary unknown content was not demonstrated, but the attack can disclose whether a secret-like message body matches a candidate. Disable IMAP compression. Update to non-vulnerable version. No publicly available exploits are known.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Open-Xchange GmbH OX Dovecot Pro

Default version status: unaffected

  • 2.3.0 to < 2.3.22.2affected
  • 3.0.0 to < 3.0.7affected
  • 3.1.0 to < 3.1.6affected

Open-Xchange GmbH OX Dovecot CE

Default version status: unaffected

  • 2.3.0 to < 2.4.5affected

References