How severe is GHSA-r4xp-prcw-77qf?

GHSA-r4xp-prcw-77qf has a CVSS score of 7.4/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-r4xp-prcw-77qf?

GHSA-r4xp-prcw-77qf affects the following packages: better-auth (npm). Ecosystems affected: npm.

How do I fix GHSA-r4xp-prcw-77qf?

Update better-auth to 1.7.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r4xp-prcw-77qf is resolved across your whole dependency graph.

How do I detect GHSA-r4xp-prcw-77qf in my npm dependencies?

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.

How do I mitigate GHSA-r4xp-prcw-77qf if there is no patch (or I can't update yet)?

Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Is GHSA-r4xp-prcw-77qf actively exploited in the wild?

No public exploit code has been indexed for GHSA-r4xp-prcw-77qf yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-r4xp-prcw-77qf?

GHSA-r4xp-prcw-77qf has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 21th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-r4xp-prcw-77qf?

GHSA-r4xp-prcw-77qf is classified as Improper Authentication (CWE-287). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-r4xp-prcw-77qf published, and has it been updated?

GHSA-r4xp-prcw-77qf was published on October 27, 2026 and was last updated on October 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

HIGH severity

better-auth: OAuth Proxy lets an attacker sign in as another userGHSA-r4xp-prcw-77qf

HIGHFix: better-auth/better-auth#11494

GHSA-r4xp-prcw-77qf is a high-severity (CVSS 7.4) Improper Authentication vulnerability in better-auth. A fix is available for better-auth — see the affected versions and patch details below.

Also known asCVE-2026-110864

Published

Oct 27, 2026

Updated

Oct 27, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
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-r4xp-prcw-77qf.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs21th percentile — riskier than 21% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-r4xp-prcw-77qf by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 396,257 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

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.

894other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

better-authnpm

11.3Mdownloads / week

Description

Am I affected?

You may be affected if you use better-auth from 1.5.0-beta.12 through versions before 1.7.7 with the OAuth Proxy plugin. You are affected only if all of these are also true:

On a participating environment, the OAuth Proxy plugin has no dedicated secret, or its secret equals that environment's global Better Auth secret.
Sign-in state is stored in a cookie (account.storeStateStrategy: "cookie"). With a database or secondary storage, this is only the case if you chose it explicitly.
Implicit account linking is on (the default).

You are not affected by this path if every participating environment uses a proxy secret distinct from its global Better Auth secret, if sign-in state is stored in the database, or if you use a version before 1.5.0-beta.12.

Summary

The OAuth Proxy plugin trusts any user profile it can decrypt. In the affected setup, Better Auth encrypts sign-in state, including data the caller chose, with the same secret and hands it to anyone who starts a social sign-in. An attacker can use this to get a fake profile for another user's email address that the proxy accepts as real.

Impact

An attacker without an account who knows a user's verified email address can sign in as that user, with that user's permissions. They can read private data, change the account, and link a provider account of their choice to it. They need no provider sign-in and no action from the victim. No availability impact is established, and a reported open redirect was not confirmed.

Patches

The fix is merged for the planned better-auth 1.7.7 release. That package is not available yet.

Upgrade all nodes handling the same cookie-backed OAuth or SAML state flow and all OAuth Proxy participants together, including the production coordinator and preview or development deployments. Keep installed Better Auth packages released alongside better-auth on the same release version. Restart pending sign-in and account-linking flows; pre-upgrade state cookies and proxy payloads are rejected. Public options and API signatures are unchanged.

Workarounds

Until you upgrade to the fixed release, apply one of these:

Set one strong OAuth Proxy secret across every environment that takes part in the proxy flow, and keep it different from each environment's global Better Auth secret.
Set account.storeStateStrategy: "database". This is already the default when a database or secondary storage is configured. If Magic Link is also enabled, switching can expose a separate cross-purpose verification-record path in affected releases. Ensure the two flows resolve to distinct stored identifiers; with built-in options, use Magic Link storeToken: "hashed" with global verification.storeIdentifier unset or "plain", or disable Magic Link or both built-in social and Generic OAuth sign-in.
Remove the OAuth Proxy plugin if you do not need it.

Setting account.accountLinking.disableImplicitLinking: true stops this path from taking over an existing account. It does not fix the underlying flaw: the callback can still accept attacker-made data as a provider identity. Apply one of the steps above as well.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`better-auth`	≥ 1.5.0-beta.12&&< 1.7.7	1.7.7`npm install better-auth@1.7.7`

Detection & mitigation playbook

Open-source dependency

Detect
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 1.7.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r4xp-prcw-77qf is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.

Frequently Asked Questions

## Am I affected? You may be affected if you use `better-auth` from 1.5.0-beta.12 through versions before 1.7.7 with the OAuth Proxy plugin. You are affected only if **all** of these are also true: - On a participating environment, the OAuth Proxy plugin has no dedicated `secret`, or its `secret` equals that environment's global Better Auth secret. - Sign-in state is stored in a cookie (`account.storeStateStrategy: "cookie"`). With a database or secondary storage, this is only the case if you chose it explicitly. - Implicit account linking is on (the default). You are not affected by this p