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Known exploited · Synacor

CVE-2025-68645: Synacor Zimbra Collaboration Suite (ZCS) PHP Remote File Inclusion Vulnerability

What it is

Synacor Zimbra Collaboration Suite (ZCS) contains a PHP remote file inclusion vulnerability that could allow for remote attackers to craft requests to the /h/rest endpoint to influence internal request dispatching, allowing inclusion of arbitrary files from the WebRoot directory.

Added January 22, 2026Due February 12, 2026CISA KEV catalog 2026.10.01

Vendor
Synacor
Product
Zimbra Collaboration Suite (ZCS)
Added to KEV
January 22, 2026
CISA due date
February 12, 2026
Ransomware use
Unknown

What CISA requires

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Forensic triage

No

What to do now

  1. Find every instance of Zimbra Collaboration Suite (ZCS) you run, including the forgotten ones, and check its version against the vendor advisory.
  2. Apply the vendor's fix or mitigation, before February 12, 2026 if you are bound by CISA's deadline, sooner if it faces the internet.
  3. Assume it was tried against you already: look for signs of exploitation from the date it was added, not from the day you patched.
  4. Until every instance is patched, block the attack at the edge: a WAF in blocking mode stops remote file inclusion attempts.

References

CVE-2025-68645 in the National Vulnerability Database

The Dome

Block it at the edge while you patch

The Dome's WAF runs the OWASP Core Rule Set in blocking mode and stops remote file inclusion attempts before they reach your application.

See the Dome

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Train the engineers who fix it

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Source: CISA Known Exploited Vulnerabilities Catalog (public domain), catalog version 2026.10.01.