GHSA-wxw3-q3m9-c3jr is a medium-severity (CVSS 5.3) Improper Authentication vulnerability in better-auth. A fix is available for better-auth — see the affected versions and patch details below.
Better Auth: OAuth callback accepts mismatched `state` when cookie-backed state storage is used without PKCE
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-wxw3-q3m9-c3jr.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-wxw3-q3m9-c3jr plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
better-authnpmDescription
Am I affected?
Users are affected if all of the following are true:
- The application uses
better-authat a version below1.6.2(or@better-auth/ssopaired with such a version). betterAuth({ account: { storeStateStrategy } })is set to"cookie". The default"database"is not affected.- The application wires at least one OAuth provider through
genericOAuth({ config })withpkce: false, or it supplies a customgetTokenortokenUrlthat does not require the storedcodeVerifier. Stock social providers with PKCE on are not affected. - The provider returns arbitrary
codevalues to the configured callback URL.
If users are on [email protected] or later, they are not affected.
Fix:
- Upgrade to
[email protected]or later (current stable is1.6.10). - If users cannot upgrade, see workarounds below.
Summary
In parseGenericState, the cookie branch decrypted the oauth_state cookie and validated expiry, but did not compare the incoming OAuth state query parameter to the nonce that generateGenericState issued at sign-in. Any callback to /api/auth/oauth2/callback/<providerId> that arrived with a forged state and any code was therefore accepted as long as the browser still held a live oauth_state cookie. With pkce: false (or any getToken path that does not enforce a code-verifier round-trip), an attacker who forced the victim to deliver an attacker-controlled authorization code to the callback would mint a session bound to the attacker's external identity in the victim's browser. Account-linking flows behaved the same way, binding the attacker's external account to an authenticated victim row.
Details
The cookie branch of parseGenericState did not compare the cookie's stored nonce to the incoming state parameter. The database branch (the default) was not affected because the verification row is keyed by state and the lookup itself enforces equality.
The fix re-binds the cookie to the nonce: generateGenericState writes oauthState: state into the encrypted payload before storage, and parseGenericState rejects when parsedData.oauthState !== state. The same primitive covers every caller (generic-oauth, social, account-link, oauth-proxy passthrough, OIDC SSO, SAML relay state).
Patches
Fixed in [email protected] via PR #8949 (commit 9deb7936a, merged 2026-04-09). The cookie branch of parseGenericState now rejects when the encrypted payload's nonce does not match the incoming state parameter; the database branch gained a defense-in-depth equality check.
Workarounds
If users cannot upgrade immediately:
- Switch
storeStateStrategyback to"database"(the default). This closes the cookie-only bypass without a code change. - Enable
pkce: trueon every affectedgenericOAuthprovider. ThecodeVerifieris the missing primitive that the attacker cannot supply.
Impact
- Forced-login (CSRF on OAuth callback): the attacker forces the victim's browser into an authenticated session bound to the attacker's external identity, allowing the attacker to observe the victim's actions inside the application.
- Persistent account linking: account-link flows bind the attacker's external account to the victim's authenticated row, granting persistent access until the link is removed.
Credit
Reported by @Jvr2022 via private advisory disclosure, and by @alavesa (PatchPilots audit) via the public duplicate issue #8897.
Resources
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | better-auth | all versions | 1.6.2npm install better-auth@1.6.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for better-auth, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update better-auth to 1.6.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wxw3-q3m9-c3jr is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-wxw3-q3m9-c3jr can be triaged on real exposure rather than presence alone.
Tailored to GHSA-wxw3-q3m9-c3jr. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-wxw3-q3m9-c3jr in your dependencies?
O3 Security finds GHSA-wxw3-q3m9-c3jr across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.