CVE-2023-28356Network attack vector

Service outage via crafted message hot loop

Published May 11, 2023 · Updated Jan 27, 2025

Denial of service in Rocket.Chat before 6.0 allows remote attackers to render a workspace unresponsive with a crafted chat message. Published sources do not identify the affected parser or function; they disclose only that a character chain traps one process in a CPU-intensive hot loop. No authentication or user interaction is required, and the documented consequence is service interruption rather than data disclosure or modification.

CVSS severity7.5
High
EPSS probability0.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Rocket.Chat before 6.0 allows remote attackers to render a workspace unresponsive with a crafted chat message. Published sources do not identify the affected parser or function; they disclose only that a character chain traps one process in a CPU-intensive hot loop. No authentication or user interaction is required, and the documented consequence is service interruption rather than data disclosure or modification.

The record

CVE
CVE-2023-28356
Published
May 11, 2023
Updated
Jan 27, 2025
Vendor
Rocket.Chat Technologies Corp.
Product
Rocket.Chat
Classifications
CWE-770, CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 27, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=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

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rocket.Chat Technologies Corp. · Rocket.Chatversion=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

Published CVSS scores

7.5HackerOneCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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