Unauthenticated account takeover via unbound SSO identifier
Published Aug 11, 2026 · Updated Aug 11, 2026
Improper authentication in usememos Memos 0.27.1 allows remote attackers to take over accounts through the OAuth2 SSO sign-in flow. The ssoCredentials branch of SignIn in server/router/api/v1/auth_service.go looks up a local user solely by an attacker-controllable IdP identifier and then issues that user's session without binding the identity to the IdP's stable subject claim. Exploitation requires OAuth2 SSO with a mapped identifier that an attacker can set to a victim's Memos username; the resulting session carries the victim's identity and role.
Summary
What happened
Improper authentication in usememos Memos 0.27.1 allows remote attackers to take over accounts through the OAuth2 SSO sign-in flow. The ssoCredentials branch of SignIn in server/router/api/v1/auth_service.go looks up a local user solely by an attacker-controllable IdP identifier and then issues that user's session without binding the identity to the IdP's stable subject claim. Exploitation requires OAuth2 SSO with a mapped identifier that an attacker can set to a victim's Memos username; the resulting session carries the victim's identity and role.
The record
- CVE
- CVE-2026-51584
- Published
- Aug 11, 2026
- Updated
- Aug 11, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-287, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 11, 2026CVE publishedPublication date reported by the CVE source.
- Aug 11, 2026Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
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Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
- CVE-2026-51584 source-level proof of conceptproof of concept · unverified
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Technologies
Your stack
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Your stack
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