Low severity · published Oct 14, 2026
CVE-2026-93637
Zimbra Collaboration Suite GraphQL Batched Authentication Bypasses Pre-Auth Rate Limiting
3.7
CVSS
0.3%
EPSS
No
On KEV
Description
An authentication rate-limit bypass in Zimbra Collaboration Suite 10.1.0 through 10.1.21 allows unauthenticated attackers to make repeated password guesses through GraphQL without incrementing Zimbra’s source-IP failure counter. GraphQL aliases allow multiple authentication attempts in one HTTP request.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 25% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
Collaboration · Zimbra
through 10.1.21 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-93637
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-93637
third-party-advisory
https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1
More from Collaboration
8.9
CVE-2026-73570
Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability
6.1
CVE-2025-66376
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting Vulnerability
6.1
CVE-2024-27443
Synacor Zimbra Collaboration Suite (ZCS) Cross-Site Scripting (XSS) Vulnerability
9.8
CVE-2023-29382
An issue in Zimbra Collaboration ZCS v.8.8.15 and v.9.0 allows an attacker to execute arbitrary code via the sfdc_preauth.jsp component
9.8
CVE-2023-29381
An issue in Zimbra Collaboration (ZCS) v.8.8.15 and v.9.0 allows a remote attacker to escalate privileges and obtain sensitive information via the password and 2FA parameters