CVE-2023-28847Network attack vector

Share-link disclosure via unthrottled password guesses

Published Apr 25, 2023 · Updated Feb 3, 2025

Improper authentication-attempt restriction in Nextcloud Server allows remote attackers to brute-force password-protected share links. PublicShareMiddleware checked invalid share tokens and passwords without invoking the brute-force throttler, so repeated failures incurred no delay or cutoff. No account is required, but the attacker must obtain a public share URL and guess its password; success exposes only content available through that share.

CVSS severity3.1
Low
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication-attempt restriction in Nextcloud Server allows remote attackers to brute-force password-protected share links. PublicShareMiddleware checked invalid share tokens and passwords without invoking the brute-force throttler, so repeated failures incurred no delay or cutoff. No account is required, but the attacker must obtain a public share URL and guess its password; success exposes only content available through that share.

The record

CVE
CVE-2023-28847
Published
Apr 25, 2023
Updated
Feb 3, 2025
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-307, T1110.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 25, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 3, 2025Record 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=>= 23.0.0, < 23.0.12.6
  2. Affected versionversion=>= 24.0.0, < 24.0.11
  3. Affected versionversion=>= 25.0.0, < 25.0.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Security Advisoriesversion=>= 23.0.0, < 23.0.12.6; version=>= 24.0.0, < 24.0.11; version=>= 25.0.0, < 25.0.5

Published CVSS scores

7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
T1110.001Password Guessing

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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