What happened
An unauthenticated calendar sender can place active markup in a COUNTER message's RFC From address. Selecting the message in Zimbra Classic triggers stored XSS, allowing the attacker to access mailbox data and act as the victim.
Affected versions
Zimbra Collaboration Suite (ZCS): before 10.1.21 (semver) Fixed: See vendor advisory.
Why it matters
Review the vendor advisory and exposure of the affected product to determine operational impact.
Detection & mitigation
- Apply vendor-provided updates or mitigations.
- Review affected product exposure and access logs.
Public PoC references
No public PoC reference has passed the current publication threshold.
Source timeline
CVE record published by NVDView source ↗
Record history
Record created from the first normalized source observation.
Metadata and source references refreshed.