CVE-2022-31183Public exploitNetwork attack vector

Unauthenticated mTLS bypass via ignored client verification

Published Aug 1, 2022 · Updated Apr 22, 2025

Improper certificate validation in Typelevel FS2 3.1.0 through 3.2.10 allows remote attackers to bypass mTLS client authentication. In the Node.js server-mode TLSSocket path, TLSContextPlatform passes requestCert but does not inspect the socket's verifyError result, so an unverified peer proceeds. Exposure requires a Scala.js application using fs2-io on Node.js to enable the nondefault requestCert setting for a server-mode socket; JVM and client-mode sockets are unaffected.

CVSS severity9.1
Critical
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in Typelevel FS2 3.1.0 through 3.2.10 allows remote attackers to bypass mTLS client authentication. In the Node.js server-mode TLSSocket path, TLSContextPlatform passes requestCert but does not inspect the socket's verifyError result, so an unverified peer proceeds. Exposure requires a Scala.js application using fs2-io on Node.js to enable the nondefault requestCert setting for a server-mode socket; JVM and client-mode sockets are unaffected.

The record

CVE
CVE-2022-31183
Published
Aug 1, 2022
Updated
Apr 22, 2025
Vendor
Typelevel
Product
FS2
Classifications
CWE-295, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 1, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 3.1.0, < 3.2.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Typelevel · FS2version=>= 3.1.0, < 3.2.11

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.1GitHub CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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