What is CVE-2026-50631?

CVE-2026-50631 is a high-severity vulnerability in Apache Cxf, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.4/10. Published 2026-06-12.

How severe is CVE-2026-50631?

High severity. CVSS v3 base score is 7.4 out of 10.

Vulnerability in Apache Cxf

CVE-2026-50631

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.

Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)

Published 2026-06-12 · last modified 2026-08-07.

CVSS v3 metric

CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (30.9th percentile), scored 2026-09-28.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 30.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001

Affected products

Apache Cxf
Apache Software Foundation Cxf — versions 4.0.0, 0, 4.2.0

Weakness classification (CWE)

CWE-367 — Time-of-check Time-of-use (TOCTOU) Race Condition

References

lists.apache.org/thread/s83t3x4r626o9h8rt0ryr1w7w53l1vv8 (vendor-advisory, Vendor Advisory)
af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)

Frequently asked questions

What is CVE-2026-50631?: CVE-2026-50631 is a high-severity vulnerability in Apache Cxf, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.4/10. Published 2026-06-12.
How severe is CVE-2026-50631?: High severity. CVSS v3 base score is 7.4 out of 10.