Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:L) | Low complexity |
| Attack requirements (AT:P) | Attack requirements present |
| Privileges required (PR:N) | No privileges required |
| User interaction (UI:P) | Passive user interaction |
| Confidentiality (VC:H) | High confidentiality impact |
| Integrity (VI:H) | High integrity impact |
| Availability (VA:N) | No availability impact |
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
About Better-Auth/Oauth-Provider
CVE-2026-53518 affects Better-Auth/Oauth-Provider, a product from Better-Auth. Before acting, confirm where Better-Auth/Oauth-Provider runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: Better Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint for the authorization_code grant redeems a single-use authorization code through a non-atomic find-then-delete sequence, allowing two concurrent requests to pass the read step and mint independent access tokens, refresh tokens, and ID tokens; legacy /oauth2/token and /mcp/token paths in oidc-provider and mcp plugins share the same primitive. This issue is fixed in version 1.6.11.
The weakness class is Race Condition. Two operations collide in timing, breaking a security assumption.
Based on its CVSS vector, the flaw can be reached over the network, needs no login, and relies on a user taking an action. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Better-Auth/Oauth-Provider |
| Affected versions | Better-Auth/Oauth-Provider from 1.6.0 before 1.6.11; Better Auth from 1.6.0 before 1.6.11 |
| Published | Jul 15, 2026 |
| Last modified | Jul 21, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | security-advisories@github.com |
How to detect it
- Inventory every instance of Better-Auth/Oauth-Provider and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Better-Auth/Oauth-Provider named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Better-Auth/Oauth-Provider to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-362: Race Condition More CVEs with this weakness
- CWE-367 More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11.
In createSessionInternal of PackageInstallerService.java, there is a possible method to remove a DPC app from a managed device without DO consent due to desync from persistence. This could lead to local escalation of privilege if a user can install a malicious app with no additional execution privileges needed. User interaction is needed for exploitation.
In Nfc::eventCallback() of Nfc.h, there is a possible use after free due to a race condition. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Server Network driver allows an unauthorized attacker to execute code over a network.
Parse Server is an open source backend that can be deployed to any infrastructure that can run Node.js. Prior to 9.6.0-alpha.11 and 8.6.37, Parse Server's built-in OAuth2 auth adapter exports a singleton instance that is reused directly across all OAuth2 provider configurations. Under concurrent authentication requests for different OAuth2 providers, one provider's token validation may execute using another provider's configuration, potentially allowing a token that should be rejected by one provider to be accepted because it is validated against a different provider's policy. Deployments that configure multiple OAuth2 providers via the oauth2: true flag are affected. This vulnerability is fixed in 9.6.0-alpha.11 and 8.6.37.
A race condition was addressed with improved handling of symbolic links. This issue is fixed in iOS 18.7.5 and iPadOS 18.7.5, iOS 26.3 and iPadOS 26.3, macOS Sequoia 15.7.4, macOS Sonoma 14.8.4, macOS Tahoe 26.3, visionOS 26.3. A shortcut may be able to bypass sandbox restrictions.
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