Insufficient Session Expiration Affecting @hotwired/turbo package, versions <8.0.21
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-HOTWIREDTURBO-15046444
- published22 Jan 2026
- disclosed20 Jan 2026
- creditSam Oliver
Introduced: 20 Jan 2026
CVE-2025-66803 (opens in a new tab)How to fix?
Upgrade @hotwired/turbo to version 8.0.21 or higher.
Overview
@hotwired/turbo is a The speed of a single-page web application without having to write any JavaScript
Affected versions of this package are vulnerable to Insufficient Session Expiration due to a race condition. An attacker can cause stale session cookies to be restored by delaying HTTP responses containing Set-Cookie headers, potentially reverting session state after it has been modified or invalidated. This is only exploitable if the application uses client-side cookie-based session storage for sessions.
Workaround
This vulnerability can be mitigated by using server-side session storage instead of client-side cookies, or by ensuring logout flows remove or disable Turbo Frame elements before invalidating sessions.