Zimbra Collaboration Suite OAuth Extension Cross-Site Request Forgery Enables Account Linking

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-93631
StatePUBLISHED
Assignerrapid7
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-23 14:17:57 UTC
Updated2026-10-23 16:44:17 UTC
DescriptionA cross-site request forgery vulnerability in the OAuth extension of Zimbra Collaboration Suite (ZCS) Network Edition allows an attacker to link an attacker-controlled external account to a victim's mailbox. The OAuth callback does not bind its state value or authorization code to the initiating Zimbra session and instead selects the destination mailbox from the browser's current authentication cookie. On a deployment with the provider configured, an attacker can induce a signed-in victim to load a callback containing a fresh code for the attacker's provider account. This creates a persistent data source that imports attacker-controlled contacts or events. With bidirectional CalDAV synchronization, appointments subsequently created or edited in the linked calendar are also disclosed to the attacker. ZCS 10.1.16 and 10.1.20 are affected.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

Problem Types: CWE-352 | CWE-352 CWE-352 Cross-Site request forgery (CSRF)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
3.1CNACVSS7.1HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Zimbra Zimbra Collaboration Suite affected 10.1.20 semver Not specified

References

ReferenceSourceLinkTags
www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1 [email protected] www.rapid7.com
wiki.zimbra.com/wiki/Zimbra_Security_Advisories [email protected] wiki.zimbra.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Jonah Burgess (CryptoCat), Senior Security Researcher, Rapid7 (en)

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