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CVE-2026-61909

Quick assessment

Affected
cyrusimap Cyrus IMAP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Cyrus IMAP 3.12.4 之前的版本中发现了一个问题。CalDAV/CardDAV 的 multiget 功能绕过了针对单个 href 的访问控制列表（ACL）。一个拥有共享访问权限的认证 DAV 用户，可以通过在 calendar-multiget 或 addressbook-multiget REPORT 请求中包含目标 href，从而读取其他用户未共享的日程事件或联系人。

CVSS 3.5 · Low

Possible ATT&CK Techniques 1 AI

T1577
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I. Basic Information for CVE-2026-61909

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
An issue was discovered in Cyrus IMAP before 3.12.4. CalDAV/CardDAV multiget bypasses a per-href ACL. An authenticated DAV user with some shared access to another user's calendar or address book could read even unshared events or contacts by including the target hrefs in a calendar-multiget or addressbook-multiget REPORT.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
未保护的候选通道
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
cyrusimap Cyrus IMAP 0 ~ 3.8.8 -

II. Public POCs for CVE-2026-61909

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III. Intelligence Information for CVE-2026-61909

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Vendor Pages for CVE-2026-61909 (4)

Same Patch Batch · cyrusimap · 2026-09-09 · 6 CVEs total

CVE-2026-61907 4.3 MEDIUM Cyrus IMAP 3.12.4前JMAP Snooze ACL绕过
CVE-2026-61911 4.3 MEDIUM Cyrus IMAP 3.12.4前Sieve邮箱存在性预言
CVE-2026-61915 4.2 MEDIUM Cyrus IMAP 3.12.4前 认证用户致CalDAV进程崩溃
CVE-2026-61910 3.5 LOW Cyrus IMAP 3.12.4前共享邮箱权限控制缺陷
CVE-2026-61908 3.1 LOW Cyrus IMAP<3.12.4 JMAP越界读堆内存

IV. Related Vulnerabilities

Same product: Cyrus IMAP
Same vendor: cyrusimap
Same weakness: CWE-420

V. Comments for CVE-2026-61909

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