In Zimbra Collaboration Suite (ZCS) 8.8.15, the URL at /h/compose accepts an attachUrl parameter that is vulnerable to Reflected XSS. This allows executing arbitrary JavaScript on the victim's machine.
Severity
CVSS 3.1
6.1 medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS
0.5% chance of exploitation in the next 30 days; higher than 42% of CVEs (scores of 2026-10-31)