CVE•Published 2026-07-15•Modified 2026-07-21•1 article on news•4 live references•NVD data

CVE-2026-53518Better-auth · Better-auth\/oauth-provider

Vulnerability data via NVD (ingested)

CVSS v3.1

8.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

EPSS percentile

Exploit Prediction Scoring System · top 61% of all CVEs

Weaknesses (CWE)

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition

Description

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.

Timeline

Published 2026-07-15

Modified 2026-07-21

External references

NVD MITRE Exploit-DB VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-53518

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Better-auth Better-auth\/oauth-provider"

All exposed Better-auth Better-auth\/oauth-provider instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Better-auth\/oauth-provider"

HTTP body or banner mentions "Better-auth\/oauth-provider" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-53518