Authorization bypass via multi-@ email domain matching
Published Apr 21, 2026 · Updated Apr 21, 2026
Authorization bypass in OAuth2 Proxy before 7.15.2 allows remote authenticated users to access protected applications via a malformed email claim. The isEmailValidWithDomains function in validator.go accepts any email ending in an allowed domain without first requiring exactly one @ character. Exposure requires email_domain enforcement plus an identity provider or claim mapping that passes malformed email values; hosted providers that enforce normal syntax are unaffected.
Summary
What happened
Authorization bypass in OAuth2 Proxy before 7.15.2 allows remote authenticated users to access protected applications via a malformed email claim. The isEmailValidWithDomains function in validator.go accepts any email ending in an allowed domain without first requiring exactly one @ character. Exposure requires email_domain enforcement plus an identity provider or claim mapping that passes malformed email values; hosted providers that enforce normal syntax are unaffected.
The record
- CVE
- CVE-2026-40574
- Published
- Apr 21, 2026
- Updated
- Apr 21, 2026
- Vendor
- OAuth2 Proxy
- Product
- OAuth2 Proxy
- Classifications
- CWE-863, T1078
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 21, 2026CVE publishedPublication date reported by the CVE source.
- Apr 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 7.15.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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