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.
CVE-2026-53518
HIGHNVD 8.17.6▼Trending — 3 sources updated this week
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 61% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
8.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.1Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.1
- EG Score
- 7.6(medium)
- EG Risk
- —
- EPSS
- 33.4%
- KEV
- Not listed
Published
July 7, 2026
Last Modified
July 21, 2026
Advisory Details (3)
Auto-updated Jul 15, 2026Patch available. Sources: github, github_commit, github_release.
github Patch Available
@better-auth/oauth-provider: OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive · Advisory · better-auth/better-auth · GitHub
https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79github_release Patch Available
v1.6.11
Patch available: better-auth/better-auth v1.6.11
https://github.com/better-auth/better-auth/releases/tag/v1.6.11github_commit
commit b4bc65a00778 (better-auth/better-auth)
Fix landed in better-auth/better-auth commit b4bc65a00778 — awaiting tagged release
https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9Vendor Advisories for CVE-2026-53518(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(2 across 1 ecosystem)
npm(2)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| better-auth | — | 1.6.11 | — |
| @better-auth/oauth-provider | — | 1.6.11 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 10× in last 7d / 12× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 17:18 UTCNVD updateCVSS v3 → 8.1
- 2026-07-21 15:25 UTCEPSS rescore
- 2026-07-20 17:08 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 02:29 UTCEPSS rescore
- 2026-07-18 10:04 UTCEPSS rescore
- 2026-07-16 17:03 UTCEPSS rescore
- 2026-07-16 02:41 UTCEG score recompute▼ 0.50
- 2026-07-15 17:28 UTCMITRE cvelistV5CVSS v3 → 7.6 · CVSS v4 → 7.6
- 2026-07-07 21:13 UTCEG score recompute
Related CVEs(same CWE)
Same CWE
10 shownCWE-362
Frequently asked(5)
What is CVE-2026-53518?
CVE-2026-53518 is a high vulnerability published on July 7, 2026. 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…
When was CVE-2026-53518 disclosed?
CVE-2026-53518 was first published in the National Vulnerability Database on July 7, 2026, with the most recent update on July 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-53518 actively exploited?
CVE-2026-53518 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 33.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-53518?
CVE-2026-53518 has a CVSS v3 base score of 8.1 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 7.6.
How do I remediate CVE-2026-53518?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-53518, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-53518
Is Your Infrastructure Affected by CVE-2026-53518?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.