CVE-2022-31183 is a critical-severity (CVSS 9.1) CWE-295 vulnerability in co.fs2:fs2-io. 1 public exploit reference exists, so weaponization risk is real. A fix is available for co.fs2:fs2-io — see the affected versions and patch details below.
mTLS client verification is skipped in fs2 on Node.js
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2022-31183.
EPSS Exploitation Probability
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.
How urgent is this, really
CVE-2022-31183 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
co.fs2:fs2-io☕co.fs2:fs2-io_2.12☕co.fs2:fs2-io_3☕co.fs2:fs2-io_2.13☕co.fs2:fs2-io_sjs1_2.13☕co.fs2:fs2-io_sjs1_3Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Impact
When establishing a server-mode TLSSocket using fs2-io on Node.js, the parameter requestCert = true is ignored, peer certificate verification is skipped, and the connection proceeds.
The vulnerability is limited to:
fs2-iorunning on Node.js. The JVM TLS implementation is completely independent.TLSSockets in server-mode. Client-modeTLSSockets are implemented via a different API.- mTLS as enabled via
requestCert = trueinTLSParameters. The default setting isfalsefor server-modeTLSSockets.
It was introduced with the initial Node.js implementation of fs2-io in v3.1.0.
Patches
A patch is released in v3.2.11. The requestCert = true parameter is respected and the peer certificate is verified. If verification fails, a SSLException is raised.
Workarounds
If using an unpatched version on Node.js, do not use a server-mode TLSSocket with requestCert = true to establish a mTLS connection.
References
- https://github.com/nodejs/node/issues/43994
- https://www.cloudflare.com/learning/access-management/what-is-mutual-tls/
For more information
If you have any questions or comments about this advisory:
- Open an issue.
- Contact the Typelevel Security Team.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | co.fs2:fs2-io | ≥ 3.1.0&&< 3.2.11 | 3.2.11co.fs2:fs2-io:3.2.11 |
| ☕Maven | co.fs2:fs2-io_2.12 | ≥ 3.1.0&&< 3.2.11 | 3.2.11co.fs2:fs2-io_2.12:3.2.11 |
| ☕Maven | co.fs2:fs2-io_3 | ≥ 3.1.0&&< 3.2.11 | 3.2.11co.fs2:fs2-io_3:3.2.11 |
| ☕Maven | co.fs2:fs2-io_2.13 | ≥ 3.1.0&&< 3.2.11 | 3.2.11co.fs2:fs2-io_2.13:3.2.11 |
| ☕Maven | co.fs2:fs2-io_sjs1_2.13 | ≥ 3.1.0&&< 3.2.11 | 3.2.11co.fs2:fs2-io_sjs1_2.13:3.2.11 |
| ☕Maven | co.fs2:fs2-io_sjs1_3 | ≥ 3.1.0&&< 3.2.11 | 3.2.11co.fs2:fs2-io_sjs1_3:3.2.11 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for co.fs2:fs2-io, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update co.fs2:fs2-io to 3.2.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2022-31183 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2022-31183 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2022-31183. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2022-31183 in your dependencies?
O3 Security finds CVE-2022-31183 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.