CVE-2026-61910Network attack vector

Authenticated mail disclosure via unchecked special-use changes

Published Sep 9, 2026 · Updated Sep 9, 2026

Incorrect authorization in Cyrus IMAP allows remote authenticated users to redirect mail into another user's shared mailbox. In releases before 3.8.8, 3.9.0 through 3.10.3, and 3.11.0 through 3.12.3, Mailbox/set accepts a special-use role change for another user's shared mailbox based only on maySetKeywords. Exploitation requires that sharing right and no existing private mailbox with the requested role; archived, snoozed, or other role assignment can route additional mail to the shared mailbox and expose it to the sharee.

CVSS severity3.5
Low
EPSS probability0.19%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Cyrus IMAP allows remote authenticated users to redirect mail into another user's shared mailbox. In releases before 3.8.8, 3.9.0 through 3.10.3, and 3.11.0 through 3.12.3, Mailbox/set accepts a special-use role change for another user's shared mailbox based only on maySetKeywords. Exploitation requires that sharing right and no existing private mailbox with the requested role; archived, snoozed, or other role assignment can route additional mail to the shared mailbox and expose it to the sharee.

The record

CVE
CVE-2026-61910
Published
Sep 9, 2026
Updated
Sep 9, 2026
Vendor
Project Cyrus
Product
Cyrus IMAP
Classifications
CWE-863
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.8.8
  2. Affected versionversion=3.11.0 <3.12.4
  3. Affected versionversion=3.9.0 <3.10.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Project Cyrus · Cyrus IMAPversion=0 <3.8.8; version=3.11.0 <3.12.4; version=3.9.0 <3.10.4

Published CVSS scores

3.5MITRECVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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