CVE-2021-32741Network attack vector

Share-token enumeration via unthrottled public mount requests

Published Jul 12, 2021 · Updated Aug 3, 2024

Rate-limit failure in Nextcloud Server versions before 19.0.13, 20.0.11, and 21.0.3 allows remote attackers to enumerate valid share tokens. MountPublicLinkController returned share-not-found responses without invoking request throttling, permitting repeated token guesses. The public endpoint requires no authentication; successful enumeration identifies existing share tokens, but direct access to shared files is not established.

CVSS severity5.3
Medium
EPSS probability1.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Rate-limit failure in Nextcloud Server versions before 19.0.13, 20.0.11, and 21.0.3 allows remote attackers to enumerate valid share tokens. MountPublicLinkController returned share-not-found responses without invoking request throttling, permitting repeated token guesses. The public endpoint requires no authentication; successful enumeration identifies existing share tokens, but direct access to shared files is not established.

The record

CVE
CVE-2021-32741
Published
Jul 12, 2021
Updated
Aug 3, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-799, T1595.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 12, 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=< 19.0.13
  2. Affected versionversion=>= 20.0.0, < 20.0.11
  3. Affected versionversion=>= 21.0.0, < 21.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Nextcloud Security Advisoriesversion=< 19.0.13; version=>= 20.0.0, < 20.0.11; version=>= 21.0.0, < 21.0.3

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/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-799Improper Control of Interaction Frequency
T1595.003Active Scanning: Wordlist Scanning

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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