CVE-2025-9485

OAuth Single Sign On – SSO (OAuth Client) <= 6.26.12 - Authentication Bypass via get_resource_owner_from_id_token()

2025-10-03 14:11

Strategic Overview

Status: Patched in 6.26.13
Affected Plugin: OAuth Single Sign On – SSO (OAuth Client)
Affected Version: <= 6.26.12
CVSS: 9.8Critical
Weakness type: CWE-347 · Improper Verification of Cryptographic Signature
CVE: CVE-2025-9485

View all OAuth Single Sign On – SSO (OAuth Client) vulnerabilities

At a glance

CVE-2025-9485 is a critical-severity Improper Verification of Cryptographic Signature vulnerability in the OAuth Single Sign On WordPress plugin, affecting versions <= 6.26.12. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 6.26.13; sites on affected versions should update now. Disclosed October 2025, reported by Jonas Benjamin Friedli.

Vulnerability Overview

The OAuth Single Sign On – SSO (OAuth Client) plugin for WordPress is vulnerable to Improper Verification of Cryptographic Signature in versions up to, and including, 6.26.12. This is due to the plugin performing unsafe JWT token processing without verification or validation in the `get_resource_owner_from_id_token` function. This makes it possible for unauthenticated attackers to bypass authentication and gain access to any existing user account - including administrators in certain configurations - or to create arbitrary subscriber-level accounts.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-347: Improper Verification of Cryptographic Signature

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

Remediation

Update to version 6.26.13, or a newer patched version

How does WordSec protect against this?

The fix is the thing that ends this: OAuth Single Sign On 6.26.13 closes this, and updating the plugin is the step that ends it.

Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2025-9485 https://www.wordfence.com/threat-intel/vulnerabilities/id/d2448afc-70d1-4dd5-b73b-62d182ee9a8a https://nvd.nist.gov/vuln/detail/CVE-2025-9485

Related records

Other vulnerabilities in OAuth Single Sign On – SSO (OAuth Client)

CVSS Vector

9.8

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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