CVE-2023-39954Network attack vector

Server impersonation via plaintext OIDC client secrets

Published Aug 10, 2023 · Updated Oct 3, 2024

Sensitive-data exposure in Nextcloud user_oidc 1.0.0 through 1.3.2 allows attackers to impersonate the server to linked servers. Provider and ID4me records persist OIDC client secrets in the database without encryption, leaving the secrets readable in snapshots. At least read access to a database snapshot is required; a recovered secret enables server impersonation toward linked OIDC servers.

CVSS severity3.8
Low
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sensitive-data exposure in Nextcloud user_oidc 1.0.0 through 1.3.2 allows attackers to impersonate the server to linked servers. Provider and ID4me records persist OIDC client secrets in the database without encryption, leaving the secrets readable in snapshots. At least read access to a database snapshot is required; a recovered secret enables server impersonation toward linked OIDC servers.

The record

CVE
CVE-2023-39954
Published
Aug 10, 2023
Updated
Oct 3, 2024
Vendor
Nextcloud GmbH
Product
Security Advisories
Classifications
CWE-311, T1552.001
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Aug 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 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=>= 1.0.0, < 1.3.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Nextcloud GmbH · Security Advisoriesversion=>= 1.0.0, < 1.3.3

Published CVSS scores

8.1NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
3.8GitHubCVSS:3.1/AV:N/AC:L/PR:H/UI:N/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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-311Missing Encryption of Sensitive Data
T1552.001Unsecured Credentials: Credentials In Files

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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