CVE-2021-32766Network attack vector

Folder enumeration via differential errors

Published Sep 7, 2021 · Updated Aug 3, 2024

Information disclosure in Nextcloud Text allows remote attackers to enumerate folders via a File Drop link. The publicFolder endpoint returned different error messages for existing and nonexistent folders, creating an error oracle that revealed folder names. Exploitation requires access to a valid upload-only share link; impact is limited to folder-existence disclosure in affected releases before 20.0.12, 21.0.0 through 21.0.3, and 22.0.0.

CVSS severity5.3
Medium
EPSS probability1.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Nextcloud Text allows remote attackers to enumerate folders via a File Drop link. The publicFolder endpoint returned different error messages for existing and nonexistent folders, creating an error oracle that revealed folder names. Exploitation requires access to a valid upload-only share link; impact is limited to folder-existence disclosure in affected releases before 20.0.12, 21.0.0 through 21.0.3, and 22.0.0.

The record

CVE
CVE-2021-32766
Published
Sep 7, 2021
Updated
Aug 3, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-209, T1083
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=< 20.0.12
  2. Affected versionversion=>= 21.0.0, < 21.0.4
  3. Affected versionversion=>= 22.0.0, < 22.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Security Advisoriesversion=< 20.0.12; version=>= 21.0.0, < 21.0.4; version=>= 22.0.0, < 22.0.1

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
5.3GitHub, Inc.CVSS: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.

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-209Generation of Error Message Containing Sensitive Information
T1083File and Directory Discovery

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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