CVE-2023-28356 — A vulnerability has been identified where a maliciously crafted message containi

A vulnerability has been identified where a maliciously crafted message containing a specific chain of characters can cause the chat to enter a hot loop on one of the processes, consuming ~120% CPU and rendering the service unresponsive.

01What is this vulnerability?

A vulnerability has been identified where a maliciously crafted message containing a specific chain of characters can cause the chat to enter a hot loop on one of the processes, consuming ~120% CPU and rendering the service unresponsive.

02Affected products

Vendor	Product	Versions
n	a / Rocket.Chat	This issue has been fixed in version 6.0> and is backported for the supported versions. Check this document for more info: https://docs.rocket.chat/resources/get-support/enterprise-support#rocket.chat-versions

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2023-05-11T00:00:00.000Z
• Last modified: 2025-01-27T16:57:01.216Z

09References

• hackerone.com — https://hackerone.com/reports/1461340