cve.bz

CVE-2026-53518

7.6 highEPSS 0.4%

High (7.6) in better-auth. EPSS 0.4% chance of exploitation in the next 30 days. Fixed in @better-auth/oauth-provider 1.6.11.

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.

Severity

CVSS 4.0

7.6 high
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

CVSS 3.1

8.1 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
EPSS
0.4% chance of exploitation in the next 30 days; higher than 35% of CVEs (scores of 2026-10-31)
CWEs
CWE-362, CWE-367
Published
Modified
Record from
the NVD, synced

Affected

Packages (OSV)

AdvisoryEcosystemPackageAffectedFixed in
GHSA-7w99-5wm4-3g79npm@better-auth/oauth-provider>=1.6.0 <1.6.111.6.11
GHSA-7w99-5wm4-3g79npmbetter-auth<1.6.111.6.11

References

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