How severe is CVE-2022-21671?

CVE-2022-21671 has a CVSS score of 8.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2022-21671?

CVE-2022-21671 affects the following packages: @replit/crosis (npm). Ecosystems affected: npm.

How do I fix CVE-2022-21671?

Update @replit/crosis to 7.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-21671 is resolved across your whole dependency graph.

How do I detect CVE-2022-21671 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @replit/crosis. 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-2022-21671 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-2022-21671?

O3 pinpoints whether CVE-2022-21671 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-2022-21671 actively exploited in the wild?

No public exploit code has been indexed for CVE-2022-21671 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-2022-21671?

CVE-2022-21671 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 62th 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-2022-21671 published, and has it been updated?

CVE-2022-21671 was published on January 11, 2022 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-2022-21671: @replit/crosis (High 8.1)

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk62th percentile+0.73%

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.

@replit/crosisnpm

28Kdownloads / week

Description

@replit/crosis is a JavaScript client that speaks Replit's container protocol. A vulnerability that involves exposure of sensitive information exists in versions prior to 7.3.1. When using this library as a way to programmatically communicate with Replit in a standalone fashion, if there are multiple failed attempts to contact Replit through a WebSocket, the library will attempt to communicate using a fallback poll-based proxy. The URL of the proxy has changed, so any communication done to the previous URL could potentially reach a server that is outside of Replit's control and the token used to connect to the Repl could be obtained by an attacker, leading to full compromise of that Repl (not of the account). This was patched in version 7.3.1 by updating the address of the fallback WebSocket polling proxy to the new one. As a workaround, a user may specify the new address for the polling host (gp-v2.replit.com) in the ConnectArgs. More information about this workaround is available in the GitHub Security Advisory.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@replit/crosis`	all versions	7.3.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @replit/crosis. 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 @replit/crosis to 7.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-21671 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-2022-21671 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-2022-21671. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

@replit/crosis is a JavaScript client that speaks Replit's container protocol. A vulnerability that involves exposure of sensitive information exists in versions prior to 7.3.1. When using this library as a way to programmatically communicate with Replit in a standalone fashion, if there are multiple failed attempts to contact Replit through a WebSocket, the library will attempt to communicate using a fallback poll-based proxy. The URL of the proxy has changed, so any communication done to the previous URL could potentially reach a server that is outside of Replit's control and the token used

O3 Security · Impact-Aware SCA

Is CVE-2022-21671 in your dependencies?

O3 detects CVE-2022-21671 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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CVE-2022-21671