CISA Adds One Known Exploited Vulnerability to Catalog
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.
CISA has added one new vulnerability to its Known Exploited Vulnerabilities (KEV) Catalog , based on evidence of active exploitation. CVE-2026-73570 Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerability This type of vulnerability is a frequent attack vector for malicious cyber actors and poses significant risks to the federal enterprise. Binding Operational Directive (BOD) 26-04: Prioritizing Security Updates Based on Risk establishes vulnerability management requirements for Federal Civilian Executive Branch (FCEB) agencies. BOD 26-04 reinforces the importance of the KEV Catalog and requires federal agencies to prioritize rapid remediation of high-risk vulnerabilities, specifically those identified by Common Vulnerabilities and Exposures (CVEs) listed in CISA’s KEV Catalog on publicly exposed assets that grant total control of the asset post-exploitation, while deferring action for lower-risk vulnerabilities. BOD 26-04 further establishes basic expectations for when agencies must check whether threat actors compromised the system before the patch was applied. While BOD 26-04 applies only to FCEB agencies, CISA encourages all organizations to adopt risk-based vulnerability management and prioritize remediation of KEV Catalog vulnerabilities . CISA will continue to add vulnerabilities to the catalog that meet the specified criteria . Aware of an exploited vulnerability not currently listed in the KEV Catalog? Submit it for potential addition through CISA’s KEV Nomination Form . Potential KEV additions must have a CVE ID, evidence of exploitation, and clear mitigation guidance.
CSIRTS triage
- 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 publicly exposed Zimbra Collaboration Suite deployments.
- Urgency
- Critical — actively exploited in the wild with total system compromise capability; federal agencies must prioritize remediation under BOD 26-04.
- Action
- Apply Zimbra security patch immediately; identify and patch all exposed Zimbra instances.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch Collaboration Suite
Get an email when a new Collaboration Suite advisory drops — max one per day, one-click unsubscribe.
Details
Original advisory: https://www.cisa.gov/news-events/alerts/2026/08/21/cisa-adds-one-known-exploited-vulnerability-catalog
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.
- Exploitation confirmedCVE-2026-73570Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 61% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-73570 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- unknownexploitedZimbra Multiple Vulnerabilitieshkcert
- unknownexploitedNCSC-2026-0324 [1.00] [M/H] Vulnerability fixed in Zimbra Collaboration Suitencsc-nl
- unknownexploitedZimbra security advisory (AV26-816) – Update 1cccs
- criticalexploitedCVE-2026-73570: Zimbra Collaboration Suite (ZCS) OS Command Injection Vulnerabilitycisa-kev
- unknownexploitedMultiple vulnerabilities in Synacor Zimbra Collaboration (August 19, 2026)cert-fr-avis
- highCVE-2026-73570: A remote code execution vulnerability exists in Zimbra Collaboration (ZCS) before 10.1.20 when…nvd
More from CISA Cybersecurity Advisories
- criticalA Tale of Two SOCs: Insights From Two Red Team Assessments2026-08-25
- criticalZoneminder2026-08-25
- criticalSiemens SIMATIC IoT2050 Advanced2026-08-25
- criticalFURUNO FA-50 Class B AIS Transponder2026-08-25
- criticalEbyte NE2-D112026-08-25