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Security Digest · Vulnerability record · Known exploited

CVE-2019-9621: Synacor Zimbra Collaboration Suite (ZCS) Server-Side Request Forgery (SSRF) Vulnerability

Exploited in the wild (CISA KEV). Zimbra Collaboration Suite before 8.6 patch 13, 8.7.x before 8.7.11 patch 10, and 8.8.x before 8.8.10 patch 7 or 8.8.x before 8.8.11 patch 3 allows SSRF via the ProxyServlet component.

CISA KEV · added 2025-07-07 CVSS 7.5 High EPSS 81.0% · p99.6

Updated By erroneo.us Security Desk12 references Seen in the digest for Jul 7, 2025

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

  • Yes, if you run Synacor Zimbra Collaboration Suite (ZCS). CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2025-07-07, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2025-07-28; treat that as the outer limit, not the target.
  • EPSS 81.0%, percentile 99.6: FIRST’s model estimates a 81.0% chance of exploitation activity in the next 30 days, higher than 99.6% of all scored CVEs (very high). EPSS is a probability, not a verdict.
  • Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

What it is

Zimbra Collaboration Suite before 8.6 patch 13, 8.7.x before 8.7.11 patch 10, and 8.8.x before 8.8.10 patch 7 or 8.8.x before 8.8.11 patch 3 allows SSRF via the ProxyServlet component.

CISA’s summary

Synacor Zimbra Collaboration Suite (ZCS) contains a server-side request forgery (SSRF) vulnerability via the ProxyServlet component.

Weakness type: CWE-918, CWE-807.

Product: Synacor Zimbra Collaboration Suite (ZCS) · Assigned by: mitre · Published: 2019-04-30

Affected and fixed versions

VendorProductAffected versions (per CVE record)
n/an/asee vendor advisory

Severity scores

Scored byCVSSScoreVector
CISA-ADP3.17.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
  • Attack vector: network (remotely reachable)
  • Attack complexity: low
  • Privileges required: none (no login)
  • User interaction: none
  • Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

  • CISA KEV: added 2025-07-07; federal due date 2025-07-28. Known ransomware use: Unknown.
  • CISA 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.
  • CISA SSVC assessment: exploitation active, automatable yes, technical impact partial.
  • FIRST EPSS (model of 2026-10-21): 81.04% probability of exploitation activity in the next 30 days; percentile 99.6.

Timeline

  • — CVE record published by mitre
  • — Added to CISA’s Known Exploited Vulnerabilities catalog
  • — CISA remediation deadline for US federal agencies
  • — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

  1. Listed in CISA KEV notes (wiki.zimbra.com) wiki.zimbra.com
  2. Listed in CISA KEV notes (wiki.zimbra.com) wiki.zimbra.com

Vulnerability records

  1. CVE.org record CVE-2019-9621 cve.org
  2. NVD entry CVE-2019-9621 nvd.nist.gov

Government

  1. CISA Known Exploited Vulnerabilities catalog entry cisa.gov

Other references from the CVE record and advisory

  1. bugzilla.zimbra.com bugzilla.zimbra.com
  2. rapid7.com rapid7.com
  3. packetstormsecurity.com packetstormsecurity.com
  4. 46693 exploit-db.com
  5. blog.zimbra.com blog.zimbra.com
  6. blog.tint0.com blog.tint0.com
  7. packetstormsecurity.com packetstormsecurity.com

All exploited Synacor vulnerabilities · Today’s Security Digest