Exploited CVEs / Synacor / CVE-2025-48700
CVE-2025-48700
Synacor Zimbra Collaboration Suite (ZCS) Cross-site Scripting Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2026-04-23 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Zimbra Security Center, linked below.
Actively exploited Synacor Zimbra Collaboration Suite (ZCS) vulnerability, Medium severity, CVSS 6.1. Added to the CISA KEV catalog 2026-04-20.
Risk summary
Updated July 30, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2025-48700
This is a stored or reflected cross-site scripting flaw in Synacor Zimbra Collaboration Suite that lets attackers run arbitrary JavaScript inside a logged-in user's webmail session, opening the door to session theft and access to mailbox contents. Despite a Medium severity rating and only 2 percent EPSS, CISA added it to the Known Exploited Vulnerabilities catalog on 2026-04-20, so the low score understates the real risk to any organization running Zimbra webmail.
Do this: Apply the current Zimbra ZCS security patch to all mail servers now and force a session reset for webmail users.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2025-48700
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2025-48700
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
CISA required action
Federal (BOD 22-01) remediation due date: 2026-04-23 (past due).
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Official fix for CVE-2025-48700
The authoritative fix and affected-version list are published by the vendor. Find the Zimbra Collaboration Suite (ZCS) advisory on Zimbra Security Center.
Common questions about CVE-2025-48700
Is CVE-2025-48700 actively exploited?
Yes. CVE-2025-48700 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2026-04-20, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 1.8%.
What is the CISA deadline and required action for CVE-2025-48700?
CISA set the federal (BOD 22-01) remediation due date at 2026-04-23, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
What fixes CVE-2025-48700?
The authoritative fix is in the vendor advisory: see Zimbra Security Center for the patched Zimbra Collaboration Suite (ZCS) versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.
Can I ask my own AI about CVE-2025-48700?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2025-48700's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).
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Authoritative references
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