Vulnerability in Synacor Zimbra Collaboration Suite
CVE-2026-73576
In Zimbra Collaboration (ZCS) before 10.1.17, weak cryptographic key generation vulnerability exists in the OnlyOffice integration. The zimbraDocumentEditingJwtSecret is generated using an insecure random number generator, resulting in insufficient entropy. An attacker who obtains a JWT signed with the generated secret may be able to recover the JWT signing secret through offline brute-force, potentially enabling JWT forgery.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.003 (23.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 23.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001
Affected products
Weakness classification (CWE)
References
- wiki.zimbra.com/wiki/Zimbra_Security_Advisories (Vendor Advisory)
- wiki.zimbra.com/wiki/Zimbra_Responsible_Disclosure_Policy (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-73576?
- CVE-2026-73576 is a medium-severity vulnerability in Synacor Zimbra Collaboration Suite, classified under CWE-1241. CVSS score: 6.3/10. Published 2026-08-13.
- How severe is CVE-2026-73576?
- Medium severity. CVSS v3 base score is 6.3 out of 10.