Zimbra Collaboration Suite up to 10.1.21 Calendar Invitation improper authorization

Summaryinfo

A vulnerability described as problematic has been identified in Zimbra Collaboration Suite up to 10.1.21. Affected by this vulnerability is an unknown functionality of the component Calendar Invitation. Executing a manipulation can lead to improper authorization. This vulnerability is registered as CVE-2026-93629. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability has been found in Zimbra Collaboration Suite up to 10.1.21 and classified as problematic. This vulnerability affects an unknown code block of the component Calendar Invitation. The manipulation with an unknown input leads to a improper authorization vulnerability. The CWE definition for the vulnerability is CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. As an impact it is known to affect integrity. CVE summarizes:

An organizer authentication vulnerability in Zimbra Collaboration Suite (ZCS) allows an unauthenticated email sender to insert calendar invitations attributed to another user. The email delivery path permits external invitations but does not verify that the message sender is authorized to use the iCalendar ORGANIZER identity. When automatic invitation insertion is enabled, a crafted REQUEST component creates an event containing attacker-selected meeting details and reminders under a forged organizer without recipient interaction. No corresponding event is created in the claimed organizer's calendar. ZCS 10.1.16 and 10.1.21 are affected.

The advisory is shared for download at wiki.zimbra.com. This vulnerability was named CVE-2026-93629 since 09/18/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/23/2026). The MITRE ATT&CK project declares the attack technique as T1548.002.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Groupware Software

Vendor

• Zimbra

Name

• Collaboration Suite

Version

• 10.1.0
• 10.1.1
• 10.1.2
• 10.1.3
• 10.1.4
• 10.1.5
• 10.1.6
• 10.1.7
• 10.1.8
• 10.1.9
• 10.1.10
• 10.1.11
• 10.1.12
• 10.1.13
• 10.1.14
• 10.1.15
• 10.1.16
• 10.1.17
• 10.1.18
• 10.1.19
• 10.1.20
• 10.1.21

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