CVE-2024-33667Public exploitNetwork attack vector

Authenticated service hang via arbitrary method invocation

Published Apr 26, 2024 · Updated Nov 25, 2024

Denial of service in Zammad before 6.3.0 allows remote authenticated users to hang the web application through a crafted iCal request. The iCal calendar endpoint passes its URL method parameter to CalendarSubscriptions#generic_call, which resolves and invokes any public Ruby method. An agent session is required; invoking Kernel#sleep across all Puma worker threads stops the service from handling requests.

CVSS severity6.5
Medium
EPSS probability0.56%
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 Zammad before 6.3.0 allows remote authenticated users to hang the web application through a crafted iCal request. The iCal calendar endpoint passes its URL method parameter to CalendarSubscriptions#generic_call, which resolves and invokes any public Ruby method. An agent session is required; invoking Kernel#sleep across all Puma worker threads stops the service from handling requests.

The record

CVE
CVE-2024-33667
Published
Apr 26, 2024
Updated
Nov 25, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-862, T1499.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 26, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 25, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:L/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.

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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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-862Missing Authorization
T1499.003Application Exhaustion Flood

Public exploit references

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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