CVE-2023-35928Network attack vector

Account takeover via cross-user session credential reuse

Published Jun 23, 2023 · Updated Dec 5, 2024

Improper privilege handling in Nextcloud Server and Enterprise Server allows remote authenticated users to take over other accounts. The files_external SessionCredentials handler reused saved session credentials without verifying that their UID matched the user requesting the external-storage mount. An authenticated user who can create FTP, Nextcloud, SFTP, or WebDAV user-scoped storage can expose another user's login credentials after that user interacts with the crafted mount.

CVSS severity8.8
High
EPSS probability0.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper privilege handling in Nextcloud Server and Enterprise Server allows remote authenticated users to take over other accounts. The files_external SessionCredentials handler reused saved session credentials without verifying that their UID matched the user requesting the external-storage mount. An authenticated user who can create FTP, Nextcloud, SFTP, or WebDAV user-scoped storage can expose another user's login credentials after that user interacts with the crafted mount.

The record

CVE
CVE-2023-35928
Published
Jun 23, 2023
Updated
Dec 5, 2024
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-274, T1555
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 23, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Nextcloud Enterprise Server >= 19.0.0, < 19.0.13.9
  2. Affected versionversion=Nextcloud Enterprise Server >= 20.0.0.0, < 20.0.14.14
  3. Affected versionversion=Nextcloud Enterprise Server >= 21.0.0.0, < 21.0.9.12
  4. Affected versionversion=Nextcloud Enterprise Server >= 22.0.0.0, < 22.2.10.12
  5. Affected versionversion=Nextcloud Enterprise Server >= 23.0.0.0, < 23.0.12.7
  6. Affected versionversion=Nextcloud Enterprise Server >= 24.0.0.0, < 24.0.12.2
  7. Affected versionversion=Nextcloud Enterprise Server >= 25.0.0, < 25.0.7
  8. Affected versionversion=Nextcloud Enterprise Server >= 26.0.0, < 26.0.2
  9. Affected versionversion=Nextcloud Server >= 25.0.0, < 25.0.7
  10. Affected versionversion=Nextcloud Server >= 26.0.0, < 26.0.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Nextcloud GmbH · Security Advisoriesversion=Nextcloud Enterprise Server >= 19.0.0, < 19.0.13.9; version=Nextcloud Enterprise Server >= 20.0.0.0, < 20.0.14.14; version=Nextcloud Enterprise Server >= 21.0.0.0, < 21.0.9.12; version=Nextcloud Enterprise Server >= 22.0.0.0, < 22.2.10.12; version=Nextcloud Enterprise Server >= 23.0.0.0, < 23.0.12.7; version=Nextcloud Enterprise Server >= 24.0.0.0, < 24.0.12.2; version=Nextcloud Enterprise Server >= 25.0.0, < 25.0.7; version=Nextcloud Enterprise Server >= 26.0.0, < 26.0.2; version=Nextcloud Server >= 25.0.0, < 25.0.7; version=Nextcloud Server >= 26.0.0, < 26.0.2

Published CVSS scores

8.4GitHubCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H
8.8NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-274Improper Handling of Insufficient Privileges
T1555Credentials from Password Stores

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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