CVE-2023-45150Public exploitNetwork attack vector

Authenticated service interruption via oversized attendee addresses

Published Oct 16, 2023 · Updated Sep 16, 2024

Resource exhaustion in Nextcloud Calendar before 4.4.4 allows remote authenticated users to make the server unresponsive via event invitations. The event-sharing path sends attacker-supplied attendee strings of megabyte scale through email-address validation without first enforcing a length limit. A low-privileged account that can invite attendees is sufficient; oversized addresses consume server resources and interrupt service.

CVSS severity4.3
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Nextcloud Calendar before 4.4.4 allows remote authenticated users to make the server unresponsive via event invitations. The event-sharing path sends attacker-supplied attendee strings of megabyte scale through email-address validation without first enforcing a length limit. A low-privileged account that can invite attendees is sufficient; oversized addresses consume server resources and interrupt service.

The record

CVE
CVE-2023-45150
Published
Oct 16, 2023
Updated
Sep 16, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Calendar
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 16, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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?

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

  1. Affected versionversion=1.0.0 <4.4.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Calendarversion=1.0.0 <4.4.4
Nextcloud GmbH · Security Advisoriesversion=>= 1.0.0, < 4.4.4

Published CVSS scores

4.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

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-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

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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