CVE-2025-58369 is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in co.fs2:fs2-io_2.12. A fix is available for co.fs2:fs2-io_2.12 — see the affected versions and patch details below.
fs2: Half-shutdown of socket during TLS handshake may result in spin loop on opposite side
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-58369.
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-2025-58369 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 376,715 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_2.12☕co.fs2:fs2-io_2.12☕co.fs2:fs2-io_2.13☕co.fs2:fs2-io_2.13☕co.fs2:fs2-io_3☕co.fs2:fs2-io_3☕co.fs2:fs2-io_0.26☕co.fs2:fs2-io_0.27+9 moreReal-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
fs2 is a compositional, streaming I/O library for Scala. Versions up to and including 2.5.12, 3.0.0-M1 through 3.12.2, and 3.13.0-M1 through 3.13.0-M6 are vulnerable to denial of service attacks though TLS sessions using fs2-io on the JVM using the fs2.io.net.tls package. When establishing a TLS session, if one side of the connection shuts down write while the peer side is awaiting more data to progress the TLS handshake, the peer side will spin loop on the socket read, fully utilizing a CPU. The CPU is consumed until the overall connection is closed, potentially shutting down a fs2-io powered server. This issue is fixed in versions 2.5.13, 3.12.1, and 3.13.0-M7.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | co.fs2:fs2-io_2.12 | ≥ 3.0.0-M1&&< 3.12.2 | 3.12.2co.fs2:fs2-io_2.12:3.12.2 |
| ☕Maven | co.fs2:fs2-io_2.12 | ≥ 3.13.0-M1&&< 3.13.0-M7 | 3.13.0-M7co.fs2:fs2-io_2.12:3.13.0-M7 |
| ☕Maven | co.fs2:fs2-io_2.13 | ≥ 3.0.0-M1&&< 3.12.2 | 3.12.2co.fs2:fs2-io_2.13:3.12.2 |
| ☕Maven | co.fs2:fs2-io_2.13 | ≥ 3.13.0-M1&&< 3.13.0-M7 | 3.13.0-M7co.fs2:fs2-io_2.13:3.13.0-M7 |
| ☕Maven | co.fs2:fs2-io_3 | ≥ 3.0.0-M1&&< 3.12.2 | 3.12.2co.fs2:fs2-io_3:3.12.2 |
| ☕Maven | co.fs2:fs2-io_3 | ≥ 3.13.0-M1&&< 3.13.0-M7 | 3.13.0-M7co.fs2:fs2-io_3:3.13.0-M7 |
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_2.12, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update co.fs2:fs2-io_2.12 to 3.12.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-58369 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-2025-58369 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-58369. 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-2025-58369 in your dependencies?
O3 Security finds CVE-2025-58369 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.