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PatchSiren cyber security CVE debrief

CVE-2016-3404 Synacor CVE debrief

CVE-2016-3404 is a high-severity vulnerability in Zimbra Collaboration that can let remote attackers affect integrity through unspecified vectors. The public record does not describe the root cause or attack path, but the issue is treated as network-reachable and requires no privileges or user interaction. Use the vendor's 8.7.0 release materials and security advisories as the remediation context.

Vendor
Synacor
Product
CVE-2016-3404
CVSS
HIGH 7.5
CISA KEV
Not listed in stored evidence
Original CVE published
2017-01-18
Original CVE updated
2026-05-13
Advisory published
2017-01-18
Advisory updated
2026-05-13

Who should care

Zimbra Collaboration administrators, email and messaging platform owners, and security teams responsible for internet-facing or business-critical mail systems. This is especially important for environments running versions in the affected range documented by the CVE and NVD records.

Technical summary

The CVE description states that Zimbra Collaboration before 8.7.0 contains an unspecified vulnerability, identified as bug 103959, that allows remote attackers to affect integrity via unknown vectors. NVD assigns CVSS v3.0 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N and labels the weakness as NVD-CWE-noinfo. In the supplied NVD CPE criteria, synacor:zimbra_collaboration_suite is marked vulnerable through version 8.6.0, while the CVE description uses the broader wording 'before 8.7.0'; the vendor's 8.7.0 release notes and security advisories are the remediation references in the corpus.

Defensive priority

High. The issue is remotely reachable, needs no authentication, and can affect integrity. Expedited patching is appropriate for any exposed Zimbra deployment, particularly where message or directory data integrity is important.

Recommended defensive actions

  • Review all Zimbra Collaboration installations and identify versions in the affected range.
  • Upgrade to a vendor-fixed release at or beyond the 8.7.0 remediation context referenced by the vendor materials.
  • If immediate upgrading is not possible, reduce exposure by restricting network access to Zimbra services and monitoring for unexpected integrity changes.
  • Validate backups and recovery procedures before and after remediation.
  • Track the vendor advisories and NVD record for any clarification or additional fix guidance.

Evidence notes

This debrief is limited to the supplied CVE/NVD corpus and the linked vendor references. The corpus does not provide a detailed root cause, exploit mechanism, or proof-of-concept. The exact vulnerable upper bound is described as 'before 8.7.0' in the CVE text, while the NVD CPE criteria enumerate vulnerability through 8.6.0; both are noted here without resolving the discrepancy beyond the source material.

Official resources

CVE-2016-3404 was published on 2017-01-18. The supplied vendor references point to Zimbra 8.7.0 release notes and Zimbra security advisories as the relevant remediation context.