CVE-2026-45364

HIGHNVD 7.37.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.3 under NVD CVSS v3. EPSS exploit probability: 0.3%, top 79% 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, nvd
7.3
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Better Auth is an authentication and authorization library for TypeScript. Prior to 1.4.17 and 1.5.0-beta.9, Better Auth's HTTP rate limiter keyed each request by the exact textual IP address it received in x-forwarded-for (or the configured IP-bearing header). IPv6 clients controlling a typical /64 allocation could rotate through 2^64 distinct source addresses without exhausting the per-address counter, defeating rate limiting on /sign-in/email, /sign-up/email, /forget-password, and every other path the limiter protects. The same bug allowed a single client to vary the textual encoding of one IPv6 address (uppercase, compression, IPv4-mapped, hex-encoded IPv4-in-IPv6) and produce multiple distinct keys. This vulnerability is fixed in 1.4.17 and 1.5.0-beta.9.

CVSS v3
7.3
EG Score
7.3(medium)
EPSS
21.3%
KEV
Not listed

Published

May 15, 2026

Last Modified

June 1, 2026

Advisory Details (5)

Auto-updated May 29, 2026
Patch available. Sources: github, github_commit, github_pr.
github Patch Available

Rate limiter keys IPv6 addresses individually and is bypassable via prefix rotation · Advisory · better-auth/better-auth · GitHub

https://github.com/better-auth/better-auth/security/advisories/GHSA-p6v2-xcpg-h6xw
github_pr

fix: set default ipv6 subnet to 64

Fix merged in better-auth/better-auth PR #7509 on 2026-01-21 — awaiting tagged release

https://github.com/better-auth/better-auth/pull/7509
github_pr Patch Available

fix(rate-limit): support IPv6 address normalization and subnet

Patch available: better-auth/better-auth v1.5.0 (PR #7470 merged 2026-01-19)

https://github.com/better-auth/better-auth/pull/7470
github_commit Patch Available

commit 57af0f7b910d (better-auth/better-auth)

Patch available: better-auth/better-auth v1.5.0 (contains commit 57af0f7b910d)

https://github.com/better-auth/better-auth/commit/57af0f7b910dcf7b1a5c0615d10b9bd56bb69bef
github_commit

commit 43e719bcc0c2 (better-auth/better-auth)

Fix landed in better-auth/better-auth commit 43e719bcc0c2 — awaiting tagged release

https://github.com/better-auth/better-auth/commit/43e719bcc0c223c7079fa0c611a9cf7ea1188254

Vendor Advisories for CVE-2026-45364(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
better-auth—1.5.0-beta.9—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 51× 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.

  1. 2026-07-12 05:46 UTCEPSS rescore
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  1. 2026-06-23 21:33 UTCEPSS rescore
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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-45364?
CVE-2026-45364 is a high vulnerability published on May 15, 2026. Better Auth is an authentication and authorization library for TypeScript. Prior to 1.4.17 and 1.5.0-beta.9, Better Auth's HTTP rate limiter keyed each request by the exact textual IP address it received in x-forwarded-for (or the configured IP-bearing header). IPv6 clients controlling a typical…
When was CVE-2026-45364 disclosed?
CVE-2026-45364 was first published in the National Vulnerability Database on May 15, 2026, with the most recent update on June 1, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-45364 actively exploited?
CVE-2026-45364 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 21.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-45364?
CVE-2026-45364 has a CVSS v3 base score of 7.3 (NVD).
How do I remediate CVE-2026-45364?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-45364, 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.

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