How severe is CVE-2025-66402?

No CVSS score has been assigned to CVE-2025-66402 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-66402?

CVE-2025-66402 affects the following packages: misskey-js (npm). Ecosystems affected: npm.

How do I fix CVE-2025-66402?

Update misskey-js to 2025.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-66402 is resolved across your whole dependency graph.

How do I detect CVE-2025-66402 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for misskey-js. 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.

How do I mitigate CVE-2025-66402 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2025-66402?

O3 pinpoints whether CVE-2025-66402 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2025-66402 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-66402 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 CVE-2025-66402?

CVE-2025-66402 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 18th 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.

When was CVE-2025-66402 published, and has it been updated?

CVE-2025-66402 was published on December 15, 2025 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2025-66402: misskey.js's export data contains private post…

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk18th percentile+0.22%

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.

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

misskey-jsnpm

3Kdownloads / week

Description

Misskey is an open source, federated social media platform. Starting in version 13.0.0-beta.16 and prior to version 2025.12.0, an actor who does not have permission to view favorites or clips can can export the posts and view the contents. Version 2025.12.0 fixes the issue.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`misskey-js`	≥ 13.0.0-beta.16&&< 2025.12.0	2025.12.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for misskey-js. 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 misskey-js to 2025.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-66402 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-2025-66402 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-2025-66402. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Misskey is an open source, federated social media platform. Starting in version 13.0.0-beta.16 and prior to version 2025.12.0, an actor who does not have permission to view favorites or clips can can export the posts and view the contents. Version 2025.12.0 fixes the issue.

O3 Security · Impact-Aware SCA

Is CVE-2025-66402 in your dependencies?

O3 detects CVE-2025-66402 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

CVE-2025-66402