CVE-2019-15623Network attack vector

Identifier disclosure via ignored lookup opt-out

Published Feb 4, 2020 · Updated Aug 5, 2024

Information exposure in Nextcloud Server 16.0.1 sends its domain and user IDs to the Nextcloud Lookup Server without consent. The lookup_server_connector schedules and retries directory publication after the global address-book setting has been disabled, ignoring that opt-out. Affected deployments disclose instance and account identifiers during background synchronization, while no additional profile fields are reported.

CVSS severity5.3
Medium
EPSS probability1.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information exposure in Nextcloud Server 16.0.1 sends its domain and user IDs to the Nextcloud Lookup Server without consent. The lookup_server_connector schedules and retries directory publication after the global address-book setting has been disabled, ignoring that opt-out. Affected deployments disclose instance and account identifiers during background synchronization, while no additional profile fields are reported.

The record

CVE
CVE-2019-15623
Published
Feb 4, 2020
Updated
Aug 5, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Server
Classifications
CWE-359
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=16.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Serverversion=16.0.1

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-359Exposure of Private Personal Information to an Unauthorized Actor

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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