CVE-2026-50631: Apache CXF: OAuth2: TOCTOU Race Condition in Refresh Token Processing
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.2.2 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.1.7 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 3.6.12 - Compensating control
If upgrade is not immediately possible, mitigate the TOCTOU race condition in Apache CXF OAuth2 refresh token processing by ensuring 'recycleRefreshTokens' is not set to false (i.e., do not allow concurrent reuse of the same Refresh Token).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-50631?
CVE-2026-50631 has a high severity rating of 7.4 according to the CVSS v3.1.
How do I fix CVE-2026-50631?
To mitigate CVE-2026-50631, ensure that the 'recycleRefreshTokens' setting is enabled to prevent the reuse of refresh tokens.
What types of applications are affected by CVE-2026-50631?
CVE-2026-50631 affects applications utilizing Apache CXF for OAuth2 implementations with improper refresh token handling.
What vulnerabilities are introduced by CVE-2026-50631?
CVE-2026-50631 introduces vulnerabilities allowing concurrent requests to bypass refresh token single-use requirements, enabling token replay attacks.
When was CVE-2026-50631 published?
CVE-2026-50631 was published on June 11, 2026.