Medium severity · published Aug 13, 2026
CVE-2026-73571
An authorization bypass vulnerability exists in Zimbra Collaboration (ZCS) before 10.1.17 due to improper authorization validation in delegated email sending functionality
4.3
CVSS
0.3%
EPSS
No
On KEV
Description
An authorization bypass vulnerability exists in Zimbra Collaboration (ZCS) before 10.1.17 due to improper authorization validation in delegated email sending functionality. An authenticated attacker can send specially crafted SOAP requests to impersonate another user and send emails without possessing the required delegation or send-as permissions. This occurs in the SaveDraftRequest SOAP handler.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 17% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
Collaboration · Zimbra
before 10.1.17 · source: vendor
ZC
Zimbra Collaboration Suite · Synacor
before 10.1.17 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73571
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-73571
Vendor Advisory
https://wiki.zimbra.com/wiki/Security_Center
Vendor Advisory
https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories
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