CVE-2026-50631 Apache CXF: OAuth2: TOCTOU Race Condition in Refresh Token Processing
Concurrent requests can bypass single-use refresh token semantics, allowing multiple valid access tokens to be generated from a single leaked token.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-50631?
CVE-2026-50631 is a high-severity vulnerability in Apache Cxf, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-367
Which versions are affected by CVE-2026-50631?
4 open source packages ship an affected version, including org.apache.cxf:cxf-rt-rs-security-oauth2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
org.apache.cxf:cxf-rt-rs-security-oauth2 Maven | All versions | 4.1.7 |
org.apache.cxf:cxf-rt-rs-security-oauth2 Maven | All versions | 4.1.7 |
org.apache.cxf:cxf-rt-rs-security-oauth2 Maven | From 4.2.0 | 4.2.2 |
org.apache.cxf:cxf-rt-rs-security-oauth2 Maven | From 4.2.0 | 4.2.2 |
Products include Apache Cxf.
How do I fix CVE-2026-50631?
Upgrade org.apache.cxf:cxf-rt-rs-security-oauth2 to a fixed version for your release line: 4.1.7 or 4.2.2.
Is CVE-2026-50631 being exploited?
There is no known exploitation of CVE-2026-50631 in the wild and no public exploit code.
Other vulnerabilities in Apache Cxf
- CVE-2012-2379 XML Signature/Encryption Not Validated in Apache CXF
- CVE-2026-66909 Apache CXF: Unsafe deserialization of inbound JMS ObjectMessage
- CVE-2026-68079 Apache CXF: DefaultEncryptingCodeDataProvider allows unlimited authorization code replay
- CVE-2026-50628 Apache CXF: OAuth2: Inverted IP Binding Check Defeats Security Control
- CVE-2025-48913 Apache CXF: Untrusted JMS configuration can lead to RCE
Sources
Also known as GHSA-83r6-96m8-r52p.