Assessment
Why it matters
CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 46.7%; technical severity is CVSS 6.1.
Zimbra Collaboration (ZCS) 8 before 8.8.15 Patch 41 allows XSS in the Zimbra Classic Web Client.
Who should care
- Teams operating Zimbra Collaboration Suite, Zimbra Collaboration Suite (ZCS)
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether Zimbra Collaboration Suite, Zimbra Collaboration Suite (ZCS) is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Treatment intelligence
Remediation intelligence
Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.
Verification noteAutomated link verification has not completed for this guidance yet.
Technical details
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CWE
- CWE-79
- Affected versions
- Synacor Zimbra Collaboration Suite (Start Including 8.8.0, End Excluding 8.8.15 | Version 8.8.15 | Version 8.8.15 | Version 8.8.15); Synacor Zimbra Collaboration Suite (ZCS)
- Fixed versions
- Synacor Zimbra Collaboration Suite (Fixed from 8.8.15)
- Published
- 31 July 2023
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
Signal timeline
- CVE published
- Added to CISA KEV
- Latest EPSS score: 46.7%
- Signal calculated at 75