How severe is GHSA-844m-cpr9-jcmh?

GHSA-844m-cpr9-jcmh has a CVSS score of 6.2/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by GHSA-844m-cpr9-jcmh?

GHSA-844m-cpr9-jcmh affects the following packages: rails_multisite (RubyGems). Ecosystems affected: RubyGems.

How do I fix GHSA-844m-cpr9-jcmh?

Update rails_multisite to 4.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-844m-cpr9-jcmh is resolved across your whole dependency graph.

How do I detect GHSA-844m-cpr9-jcmh in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rails_multisite. 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-844m-cpr9-jcmh 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-844m-cpr9-jcmh?

O3 pinpoints whether GHSA-844m-cpr9-jcmh 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-844m-cpr9-jcmh actively exploited in the wild?

No public exploit code has been indexed for GHSA-844m-cpr9-jcmh 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-844m-cpr9-jcmh?

GHSA-844m-cpr9-jcmh has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 44th 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.

What type of vulnerability is GHSA-844m-cpr9-jcmh?

GHSA-844m-cpr9-jcmh is classified as Information Exposure (CWE-200), CWE-565 (CWE-565), Broken Cryptographic Algorithm (CWE-327). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-844m-cpr9-jcmh published, and has it been updated?

GHSA-844m-cpr9-jcmh was published on November 15, 2021 and was last updated on March 13, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎 RubyGems

GHSA-844m-cpr9-jcmh

MEDIUM

Rails Multisite secure/signed cookies share secrets between sites in a multi-site application

Also known asCVE-2021-41263

Published

Nov 15, 2021

Updated

Mar 13, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk44th percentile+0.41%

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

💎rails_multisite

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

Impact

This vulnerability impacts any Rails applications using rails_multisite alongside Rails' signed/encrypted cookies. Depending on how the application makes use of these cookies, it may be possible for an attacker to re-use cookies on different 'sites' within a multi-site Rails application.

Patches

The issue has been patched in v4 of the rails_multisite gem. Note that this upgrade will invalidate all previous signed/encrypted cookies. The impact of this invalidation will vary based on the application architecture.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`rails_multisite`	all versions	4.0.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rails_multisite. 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 rails_multisite to 4.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-844m-cpr9-jcmh 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-844m-cpr9-jcmh 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-844m-cpr9-jcmh. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact This vulnerability impacts any Rails applications using `rails_multisite` alongside Rails' signed/encrypted cookies. Depending on how the application makes use of these cookies, it may be possible for an attacker to re-use cookies on different 'sites' within a multi-site Rails application. ### Patches The issue has been patched in v4 of the `rails_multisite` gem. Note that this upgrade will invalidate all previous signed/encrypted cookies. The impact of this invalidation will vary based on the application architecture.

O3 Security · Impact-Aware SCA

Is GHSA-844m-cpr9-jcmh in your dependencies?

O3 detects GHSA-844m-cpr9-jcmh across RubyGems 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