# CVE-2026-121802: CVE-2026-121802

Status: published. Published: 2026-11-04. Updated: 2026-11-04.

@better-auth/expo before 1.7.16 allows certain account-takeover outcomes (e.g., unauthenticated changes of any account's email address), because it signs a caller-supplied state value without checking whether that value had been issued by the server. NOTE: the application secret must be rotated after updating to a fixed version.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- better-auth / Better Auth (%40better-auth/expo): ≥ 0; < 1.7.16 (affected, semver). Source: CNA: mitre

## Severity and prioritization

- CVSS 3.1: 9.1 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N; source: CNA: mitre

- CVSS 3.1: 9.1 (critical); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N; source: NVD: cve@mitre.org

- CISA KEV: No listing in collected sources

- EPSS: 0.20% as of 2026-11-04; percentile 10.38%

- SSVC: Not available

- Weaknesses: CWE-346

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/better-auth/better-auth/security/advisories/GHSA-4wq4-2ppv-q3hg (CNA: mitre)

- https://github.com/better-auth/better-auth/blob/main/packages/expo/CHANGELOG.md (CNA: mitre)

- https://github.com/better-auth/better-auth/releases/tag/v1.7.16 (CNA: mitre)

- https://github.com/better-auth/better-auth/blob/main/packages/expo/CHANGELOG.md (cve@mitre.org)

- https://github.com/better-auth/better-auth/releases/tag/v1.7.16 (cve@mitre.org)

- https://github.com/better-auth/better-auth/security/advisories/GHSA-4wq4-2ppv-q3hg (cve@mitre.org)

## Provenance

- CNA: mitre: https://www.cve.org/CVERecord?id=CVE-2026-121802; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121802; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-121802; retrieved 2026-11-05; source updated Not reported

Revision: e268cc7c14f6300bae5d25c2c612546df2e541aacbce86f8bf7c7faaa25246b4

Canonical: https://y2.dev/cve/CVE-2026-121802

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