CVE-2023-29000Network attack vector

Encrypted-file disclosure via unchecked certificate-key binding

Published Apr 4, 2023 · Updated Feb 11, 2025

Improper certificate validation in Nextcloud Desktop Client 3.0.0 through pre-3.7.0 versions allows remote attackers to read E2EE files. The end-to-end encryption path accepts a server-supplied user certificate without checking that its public key matches the user's private key. Reachability requires E2EE file synchronization with a malicious server; the server operator can decrypt files encrypted under the substituted key.

CVSS severity5.4
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Nextcloud Desktop Client 3.0.0 through pre-3.7.0 versions allows remote attackers to read E2EE files. The end-to-end encryption path accepts a server-supplied user certificate without checking that its public key matches the user's private key. Reachability requires E2EE file synchronization with a malicious server; the server operator can decrypt files encrypted under the substituted key.

The record

CVE
CVE-2023-29000
Published
Apr 4, 2023
Updated
Feb 11, 2025
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-295
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 4, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 11, 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=>= 3.0.0, < 3.7.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nextcloud GmbH · Security Advisoriesversion=>= 3.0.0, < 3.7.0

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
5.4GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/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-295Improper Certificate Validation

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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