How severe is GHSA-496g-mmpw-j9x3?

GHSA-496g-mmpw-j9x3 has a CVSS score of 6.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-496g-mmpw-j9x3?

GHSA-496g-mmpw-j9x3 affects the following packages: misskey-js (npm). Ecosystems affected: npm.

How do I fix GHSA-496g-mmpw-j9x3?

Update misskey-js to 2025.12.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-496g-mmpw-j9x3 is resolved across your whole dependency graph.

How do I detect GHSA-496g-mmpw-j9x3 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 GHSA-496g-mmpw-j9x3 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 GHSA-496g-mmpw-j9x3?

O3 pinpoints whether GHSA-496g-mmpw-j9x3 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 GHSA-496g-mmpw-j9x3 actively exploited in the wild?

No public exploit code has been indexed for GHSA-496g-mmpw-j9x3 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-496g-mmpw-j9x3?

GHSA-496g-mmpw-j9x3 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 GHSA-496g-mmpw-j9x3 published, and has it been updated?

GHSA-496g-mmpw-j9x3 was published on December 15, 2025 and was last updated on February 3, 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

GHSA-496g-mmpw-j9x3

MEDIUM

misskey.js's export data contains private post data

Also known asCVE-2025-66402

Published

Dec 15, 2025

Updated

Feb 3, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

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

Summary

After adding private posts (followers, direct) that you do not have permission to view to your favorites or clips, you can export them to view the contents of the private posts.

PoC

Create an account (X) for testing and an account (Y) for private posts on the same server.
Send appropriate content from Y using "Follow"
Send appropriate content to any user using "Nominate" from Y
Obtain the URLs for the two posts above using Y's account.
Query the URLs for the two posts using X and add them to your favorites or clips.
Export your favorites or clips using X.
Check the exported data.

Note: Verified in v2025.11.1

Impact

This could allow an attacker to view the contents of private posts. If you have pinned private posts, this could be a real problem, as the ID of the private post can be obtained by viewing the user page on the original server.

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 GHSA-496g-mmpw-j9x3 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 GHSA-496g-mmpw-j9x3 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 GHSA-496g-mmpw-j9x3. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary After adding private posts (followers, direct) that you do not have permission to view to your favorites or clips, you can export them to view the contents of the private posts. ### PoC 1. Create an account (X) for testing and an account (Y) for private posts on the same server. 2. Send appropriate content from Y using "Follow" 3. Send appropriate content to any user using "Nominate" from Y 4. Obtain the URLs for the two posts above using Y's account. 5. Query the URLs for the two posts using X and add them to your favorites or clips. 6. Export your favorites or clips using X. 7

O3 Security · Impact-Aware SCA

Is GHSA-496g-mmpw-j9x3 in your dependencies?

O3 detects GHSA-496g-mmpw-j9x3 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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