High severity · published Jun 12, 2026
CVE-2026-50631
Apache CXF: OAuth2: TOCTOU Race Condition in Refresh Token Processing
7.4
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 22% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
AC
Apache CXF · Apache Software Foundation
4.2.0 before 4.2.2; 4.0.0 before 4.1.7; before 3.6.12 · source: vendor
CX
Cxf · Apache
before 4.1.7; 4.2.0 before 4.2.2 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-50631
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-50631
Vendor Advisory
https://lists.apache.org/thread/s83t3x4r626o9h8rt0ryr1w7w53l1vv8
Mailing List
http://www.openwall.com/lists/oss-security/2026/06/11/8
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