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

criticalknown exploitedpublic exploitCVE-2026-73570
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
Zimbra Collaboration Suite (ZCS) contains an OS command injection vulnerability which could allow an unauthenticated attacker to send specially crafted SMTP requests that may result in execution of arbitrary operating system commands as the Zimbra user.

CSIRTS triage

vendor: Zimbraproduct: Collaboration SuiteRemote code execution
What
OS command injection vulnerability allowing unauthenticated attackers to execute arbitrary operating system commands via specially crafted SMTP requests.
Who is affected
Unauthenticated attackers can exploit all versions of Zimbra Collaboration Suite.
Urgency
Critical — actively exploited with ability to gain complete system control; immediate remediation required.
Action
Upgrade to patched version immediately when available.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
CISA Known Exploited Vulnerabilities (US · database · site)
Severity
critical
Published
2026-08-21
Exploitation
Observed in the wild (CISA KEV)

Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-73570

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-73570coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Zimbra Collaboration Suite

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

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