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CVE-2025-71404 — better-auth

Fix: better-auth/better-auth@05ada0b

CVE-2025-71404 is a Cross-site Scripting (XSS) vulnerability in better-auth. A fix is available for better-auth — see the affected versions and patch details below.

better-auth before 1.1.16 Reflected XSS via error parameter

Also known asGHSA-9x4v-xfq5-m8x5
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • 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 CVE-2025-71404.

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk
0.00%0.41%0.81%1.22%0.4%0.5%0.7%0.7%Sep 26Nov 26Nov 26

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

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.

914other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
better-authnpm
18.7Mdownloads / week

Description

Summary

The better-auth /api/auth/error page was vulnerable to HTML injection, resulting in a reflected cross-site scripting (XSS) vulnerability.

Details

The value of error URL parameter was reflected as HTML on the error page: https://github.com/better-auth/better-auth/blob/05ada0b79dbcac93cc04ceb79b23ca598d07830c/packages/better-auth/src/api/routes/error.ts#L81

Impact

An attacker who exploited this vulnerability by coercing a user to visit a specially-crafted URL could execute arbitrary JavaScript in the context of the user's browser.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmbetter-auth≥ 0.0.2&&< 1.1.161.1.16npm install better-auth@1.1.16

Detection & mitigation playbook

Open-source dependency

  1. 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.

  2. Fix

    Update better-auth to 1.1.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-71404 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### Summary The better-auth `/api/auth/error` page was vulnerable to HTML injection, resulting in a reflected cross-site scripting (XSS) vulnerability. ### Details The value of `error` URL parameter was reflected as HTML on the error page: https://github.com/better-auth/better-auth/blob/05ada0b79dbcac93cc04ceb79b23ca598d07830c/packages/better-auth/src/api/routes/error.ts#L81 ### Impact An attacker who exploited this vulnerability by coercing a user to visit a specially-crafted URL could execute arbitrary JavaScript in the context of the user's browser.
O3 Security · Impact-Aware SCA

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CVE-2025-71404: better-auth XSS — Fixed in 1.1.16