What’s Vulnerable › Vulnerabilities

CVE-2026-50631: Apache CXF: OAuth2: TOCTOU Race Condition in Refresh Token Processing

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-12 · updated 2026-10-26
• Weakness: CWE-367

Description

A race condition in AbstractOAuthDataProvider allows concurrent requests using the same Refresh Token to bypass single-use semantics and generate multiple valid Access Tokens, when 'recycleRefreshTokens' is set to false. A leaked refresh token can be replayed concurrently by multiple attackers or threads. Users are recommended to upgrade to versions 4.2.2 or 4.1.7 or 3.6.12, which fixes this issue.

Affected products

• Apache Software Foundation Apache CXF: before 4.1.7; from 4.2.0 before 4.2.2 — fixed in 4.1.7, 4.2.2

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache CXF 4.1.7, 4.2.2. Check the vendor advisory for mitigations.

References

• https://lists.apache.org/thread/s83t3x4r626o9h8rt0ryr1w7w53l1vv8
• http://www.openwall.com/lists/oss-security/2026/06/11/8

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