CVE-2022-39052

What it actually does

Specially crafted inbound email containing an excessive number of recipients triggers resource exhaustion during message parsing and processing, resulting in denial of service.

Why it matters to the business

The ticketing platform becomes unavailable, halting customer support operations and internal workflows until the service is restarted or the load subsides.

How an attack unfolds

An unauthenticated remote attacker composes an email addressed to a large number of recipients, delivers it to the OTRS mail interface, and causes the application to consume excessive CPU or memory while handling the message, rendering the system unresponsive.

How to fix it

Apply vendor patches as soon as they become available; until then, deploy upstream mail filters or MTA rules that reject or quarantine messages with abnormally high recipient counts before they reach OTRS.

How to confirm the fix worked

Replay test messages with increasing recipient counts in a lab instance while monitoring CPU, memory, and queue lengths; confirm that patched or filtered systems remain responsive and that no crash or hang occurs.

Typical attack path

1. Craft an email message containing hundreds or thousands of recipient addresses
2. Deliver the message via SMTP to the OTRS mail gateway
3. Trigger the parsing routine that iterates over all recipients
4. Exhaust available resources and induce service denial

How to detect it

Inspect mail-server and application logs for inbound messages that list an unusually large number of recipients; correlate with sudden spikes in process resource consumption or queue backlogs around the same timestamps.

• mail.log entries showing To: headers with hundreds of addresses
• OTRS email parser process consuming >90% CPU for extended periods
• sudden growth in the OTRS email queue without corresponding ticket creation

What your security team should do

• Implement recipient-count limits at the MTA or spam-filter layer immediately
• Add monitoring alerts for sudden spikes in email-processing CPU or memory usage
• Track vendor advisory channels for the release of fixed OTRS packages and schedule upgrades
• Review and tighten mail-acceptance policies to reduce the attack surface