CVE-2025-66803
MEDIUMCVE-2025-66803 is a medium-severity (CVSS 4.8) CWE-362 vulnerability in @hotwired/turbo. O3 Security confirms whether CVE-2025-66803 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Turbo Frame responses can restore stale session cookies
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@hotwired/turbonpmDescription
Race condition in the turbo-frame element handler in Hotwired Turbo before 8.0.x causes logout operations to fail when delayed frame responses reapply session cookies after logout. This can be exploited by remote attackers via selective network delays (e.g. delaying requests based on sequence or timing) or by physically proximate attackers when the race condition occurs naturally on shared computers.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @hotwired/turbo | all versions | 8.0.21 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @hotwired/turbo. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update @hotwired/turbo to 8.0.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-66803 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-66803 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-66803. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-66803 in your dependencies?
O3 detects CVE-2025-66803 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.