CVE-2021-32703Network attack vector

Share-token enumeration via unthrottled shareinfo requests

Published Jul 12, 2021 · Updated Aug 3, 2024

Improper interaction-frequency control in Nextcloud Server before 19.0.13, 20.0.11, or 21.0.3 allows remote attackers to enumerate share tokens. The public ShareInfoController.info path returned distinct 404 and 403 responses for nonexistent, password-protected, or unreadable tokens without marking those failures for brute-force throttling. No authentication or user interaction is required; repeated requests identify potentially valid tokens but do not disclose shared content by themselves.

CVSS severity5.3
Medium
EPSS probability1.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper interaction-frequency control in Nextcloud Server before 19.0.13, 20.0.11, or 21.0.3 allows remote attackers to enumerate share tokens. The public ShareInfoController.info path returned distinct 404 and 403 responses for nonexistent, password-protected, or unreadable tokens without marking those failures for brute-force throttling. No authentication or user interaction is required; repeated requests identify potentially valid tokens but do not disclose shared content by themselves.

The record

CVE
CVE-2021-32703
Published
Jul 12, 2021
Updated
Aug 3, 2024
Vendor
Nextcloud GmbH
Product
Nextcloud Security Advisories
Classifications
CWE-799, CWE-307, T1110
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

5.3GitHub, 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
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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-799Improper Control of Interaction Frequency
CWE-307Improper Restriction of Excessive Authentication Attempts
T1110Brute Force

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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