CVE-2024-37887Network attack vector

Private event disclosure via incomplete recurrence masking

Published Jun 14, 2024 · Updated Aug 2, 2024

Improper access control in Nextcloud Server allows remote authenticated users to read private recurrence exceptions in shared calendars. CalendarObject::createConfidentialObject masks only the first event-like component instead of iterating over every VEVENT, leaving recurrence components unchanged. A sharee must have authenticated access to the shared calendar, and the disclosed data is limited to private recurrence-exception details.

CVSS severity3.5
Low
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Nextcloud Server allows remote authenticated users to read private recurrence exceptions in shared calendars. CalendarObject::createConfidentialObject masks only the first event-like component instead of iterating over every VEVENT, leaving recurrence components unchanged. A sharee must have authenticated access to the shared calendar, and the disclosed data is limited to private recurrence-exception details.

The record

CVE
CVE-2024-37887
Published
Jun 14, 2024
Updated
Aug 2, 2024
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-284, T1213
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 14, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 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=>= 27.0.0, < 27.1.10
  2. Affected versionversion=>= 27.0.0, < 28.0.6
  3. Affected versionversion=>= 27.0.0, < 29.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Security Advisoriesversion=>= 27.0.0, < 27.1.10; version=>= 27.0.0, < 28.0.6; version=>= 27.0.0, < 29.0.1

Published CVSS scores

3.5GitHub Security AdvisoriesCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N
3.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1213Data from Information Repositories

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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