CVE-2026-61909Network attack vector

Cross-user data disclosure via unchecked multiget hrefs

Published Sep 9, 2026 · Updated Sep 9, 2026

Authorization bypass in Cyrus IMAP before 3.8.8, 3.9.0 through 3.10.3, and 3.11.0 through 3.12.3 exposes unshared DAV data. Multiget REPORT handling checks access to the shared collection but does not enforce each supplied href ACL before returning its event or contact. Remote authenticated users need some shared access and knowledge of target hrefs; the result is read-only cross-user disclosure.

CVSS severity3.5
Low
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Cyrus IMAP before 3.8.8, 3.9.0 through 3.10.3, and 3.11.0 through 3.12.3 exposes unshared DAV data. Multiget REPORT handling checks access to the shared collection but does not enforce each supplied href ACL before returning its event or contact. Remote authenticated users need some shared access and knowledge of target hrefs; the result is read-only cross-user disclosure.

The record

CVE
CVE-2026-61909
Published
Sep 9, 2026
Updated
Sep 9, 2026
Vendor
Project Cyrus
Product
Cyrus IMAP
Classifications
CWE-420, T1213
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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-420Unprotected Alternate Channel
T1213Data from Information Repositories

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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