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Weekly Signal
Live intelligence Updated 20 Aug 2026 · 23:29 UTC

Synacor · Zimbra Collaboration Suite, Zimbra Collaboration Suite (ZCS)

CVE-2025-68645

Synacor Zimbra Collaboration Suite (ZCS) PHP Remote File Inclusion Vulnerability

Recommended action

Validate affected assets and exposure now, then remediate on an accelerated schedule. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

View response plan
CVSS8.8
EPSS34.4%
KEVYes
ExploitationConfirmed exploitation
RemediationFixed release identified ↓

Assessment

Why it matters

CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 34.4%; technical severity is CVSS 8.8.

A Local File Inclusion (LFI) vulnerability exists in the Webmail Classic UI of Zimbra Collaboration (ZCS) 10.0 and 10.1 because of improper handling of user-supplied request parameters in the RestFilter servlet. An unauthenticated remote attacker can craft requests to the /h/rest endpoint to influence internal request dispatching, allowing inclusion of arbitrary files from the WebRoot directory.

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

  1. Confirm whether Zimbra Collaboration Suite, Zimbra Collaboration Suite (ZCS) is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Treatment intelligence

Remediation intelligence

Not yet verified

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.

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Required Action

Technical details

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE
CWE-98
Affected versions
Synacor Zimbra Collaboration Suite (Start Including 10.0.0, End Excluding 10.0.18 | Start Including 10.1.0, End Excluding 10.1.13); Synacor Zimbra Collaboration Suite (ZCS)
Fixed versions
Synacor Zimbra Collaboration Suite (Fixed from 10.0.18, 10.1.13)
Published
22 December 2025
Attack vector
Network
Privileges required
None
User interaction
Required

Signal timeline

  1. CVE published
  2. Added to CISA KEV
  3. Latest EPSS score: 34.4%
  4. Signal calculated at 76

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.