CVE-2026-73570: Zimbra ZCS zimbra-snmp notification command injection (unauthenticated RCE)

Exploited in the wild High 8.9 EPSS 71.7% Zimbra Collaboration

Zimbra Collaboration (ZCS) before 10.1.20 has a command injection in the SNMP monitoring component: when the optional zimbra-snmp package is installed and SNMP notifications are enabled, an unauthenticated attacker can send crafted SMTP requests that run OS commands as the zimbra user. Zimbra shipped the permanent fix in ZCS 10.1.20 on July 20, 2026, after an earlier advisory on June 26, 2026. CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-21.

CVE-2026-73570CVE identifier
8.9CVSS 3.1 base score (high)
2026-08-21added to CISA's exploited list (US federal deadline 2026-08-24)
71.7%EPSS: chance of exploitation in the next 30 days (higher than 99% of CVEs)
2026-08-13published

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

Check whether you run Zimbra Collaboration and which version (commands below).
Install the fixed version for your system: see “Patch it” below.
Restart ZCS as the zimbra user (zmcontrol restart) on each node after the patch packages are installed; Zimbra patches cannot be rolled back, so take a full backup first.
Because this flaw is being exploited, also check the server for signs of compromise.

Affected and fixed versions

Affected:

Zimbra Collaboration before 10.1.20 (with zimbra-snmp installed and SNMP notifications enabled)

Fixed in:

Zimbra Collaboration 10.1.20 (zimbra-patch 10.1.20.1783418035-2)

Am I affected?

su - zimbra -c 'zmcontrol -v'
dpkg -l 'zimbra-snmp*' 2>/dev/null | grep ^ii
rpm -qa 'zimbra-snmp*'

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

Debian

not in distro repos: vendor repository

Ubuntu

# as root, on every node in order: LDAP, LDS, MTA, Proxy, Mailbox
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 5234D2B73B6996C7
apt-get update
apt upgrade
# where installed, also:
apt-get install zimbra-snmp-components
su - zimbra -c 'zmcontrol restart'

RHEL, AlmaLinux, Rocky, Oracle

# as root, on every node in order: LDAP, LDS, MTA, Proxy, Mailbox
yum clean metadata
yum check-update
yum update
# where installed, also:
yum install zimbra-snmp-components
su - zimbra -c 'zmcontrol restart'

Fedora

not supported

SUSE / openSUSE

not supported

Amazon Linux

not supported

Arch Linux

not supported

Alpine

not supported

FreeBSD

not supported

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

CISA required action: 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.

https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories ; https://blog.zimbra.com/2026/07/patch-release-update-zimbra-10-1-20/ ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-73570

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC and reviewed by an editor. Always confirm with your vendor's advisory.