CVE-2026-73570 — Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

US federal deadline: Aug 24, 2026 — passed 52 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Synacor Zimbra Collaboration Suite, Zimbra Collaboration).
2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
3. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
4. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
5. EPSS ahead of 99% of scored CVEs: prioritize it in the patch queue.
6. Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-78 · OS Command Injection

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 12, 2026 → Oct 14, 2026 · 3 reading(s) · max 71.66%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
• Look for parameters with command/query metacharacters and unexpected child processes of the service.
• Hunt retroactively in logs from before Aug 21, 2026 (KEV listing): exploitation may have started earlier.

Timeline

What happened to this CVE, newest first.

• 2026
• Affected products added · synacor/zimbra collaboration suite
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · Published → Analyzed
  Oct 13, 2026 · NIST National Vulnerability Database
• Record published
  Oct 13, 2026
• Affected products added · zimbra/collaboration
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• CVSS changed · 8.9
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Source status changed · → Published
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Added to CISA KEV (detected)
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• Record created in this database
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• Added to CISA KEV catalog
  Aug 20, 2026 · CISA
• CVE published
  Aug 13, 2026 · mitre

Source activity

Repeated readings are counted rather than listed.

• 3× References added · Oct 13, 2026 – Oct 13, 2026
• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

7 on the record

• wiki.zimbra.com/wiki/Zimbra_Security_Advisories
  Vendor Advisory, CVE Program (cve.org) e CISA ADP
• www.cisa.gov/known-exploited-vulnerabilities-catalog
  US Government Resource, NIST National Vulnerability Database
• moje.cert.pl/komunikaty/2026/145/aktywnie-wykorzystywana-podatnosc-w-zimbra-collab
  GitHub Security Advisories
• moje.cert.pl/komunikaty/2026/145/aktywnie-wykorzystywana-podatnosc-w-zimbra-collab
  Third Party Advisory, NIST National Vulnerability Database
• github.com/advisories/GHSA-jqh7-pchh-v74j
  GitHub Security Advisories
• nvd.nist.gov/vuln/detail/CVE-2026-73570
  GitHub Security Advisories
• wiki.zimbra.com/wiki/Security_Center
  Release Notes, CVE Program (cve.org) e CISA ADP

Elsewhere on this site

Related CVEs (same products)

• Medium CVE-2026-73574 Incorrect Resource Transfer Between Spheres in Synacor Zimbra Collaboration Suite Aug 13, 2026
• Medium CVE-2026-73576 In Zimbra Collaboration (ZCS) before 10.1.17, weak cryptographic key generation… Aug 13, 2026
• Medium CVE-2026-73571 Incorrect Authorization in Synacor Zimbra Collaboration Suite Aug 13, 2026
• Low CVE-2026-73575 Cross-Site Request Forgery (CSRF) in Synacor Zimbra Collaboration Suite Aug 13, 2026
• Medium CVE-2026-73573 In Zimbra Collaboration (ZCS) before 10.1.17, a path traversal vulnerability exists in… Aug 13, 2026
• Medium CVE-2026-73572 Cross-site Scripting (XSS) in Synacor Zimbra Collaboration Suite Aug 13, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No fixed version, patch or mitigation documented.
• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-73570 is "Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability", rated High. It affects Zimbra Collaboration Suite (Synacor); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 8.9 describes technical severity. EPSS 71.66% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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