# FS2 half-shutdown of socket during TLS handshake may result in spin loop on opposite side Advisory record · `GHSA-rrw2-px9j-qffj` - **Identifiers:** `GHSA-rrw2-px9j-qffj` · `CVE-2025-58369` - **State:** Confirmed - **Severity:** CVSS 5.3 Medium - **Critical:** No - **Weakness (CWE):** [CWE-400](https://cwe.mitre.org/data/definitions/400.html) - **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md) - **Published:** 5 Sept 2025 - **Updated:** 7 Nov 2025 - **Reviewed by a person:** No Published by the GitHub Advisory Database at 5 Sept 2025, 20:58 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. ## Affected packages - `co.fs2:fs2-io_2.12` (Maven): affected `>=3.0.0-M1, <3.12.2 || >=3.13.0-M1, <3.13.0-M7 || <2.5.13`; fixed in `3.12.2`, `3.13.0-M7`, `2.5.13` - `co.fs2:fs2-io_2.13` (Maven): affected `>=3.0.0-M1, <3.12.2 || >=3.13.0-M1, <3.13.0-M7 || <2.5.13`; fixed in `3.12.2`, `3.13.0-M7`, `2.5.13` - `co.fs2:fs2-io_3` (Maven): affected `>=3.0.0-M1, <3.12.2 || >=3.13.0-M1, <3.13.0-M7 || <2.5.13`; fixed in `3.12.2`, `3.13.0-M7`, `2.5.13` - `co.fs2:fs2-io_0.26` (Maven): affected `all versions`; no fixed version yet - `co.fs2:fs2-io_0.27` (Maven): affected `all versions`; no fixed version yet - `co.fs2:fs2-io_2.11` (Maven): affected `all versions`; no fixed version yet - `co.fs2:fs2-io_2.12.0-M4` (Maven): affected `all versions`; no fixed version yet - `co.fs2:fs2-io_2.12.0-RC1` (Maven): affected `all versions`; no fixed version yet - `co.fs2:fs2-io_2.12.0-M5` (Maven): affected `all versions`; no fixed version yet - `co.fs2:fs2-io_2.12.0-RC2` (Maven): affected `all versions`; no fixed version yet - `co.fs2:fs2-io_2.13.0-M5` (Maven): affected `all versions`; no fixed version yet ## Machine-written summary Summary written by Claude Haiku from the source advisory. Not reviewed by a person. > The fs2-io package (Maven co.fs2 artifacts, Scala 2.12, 2.13 and 3) is vulnerable in versions from 3.0.0-M1 up to 3.12.2 and from 3.13.0-M1 up to 3.13.0-M7, and in versions below 2.5.13. An attacker who can open TCP connections to a TLS server built on fs2-io, such as an ember-based http4s HTTPS server, can half-close a connection during the TLS handshake and make the peer spin on a socket read, consuming a CPU until the connection closes, which enables denial of service. Upgrade to 3.12.2, 3.13.0-M7 or 2.5.13. No workaround is given. Other listed fs2-io artifacts have no fixed version listed. Written 7 Nov 2026. ## Not analysed yet We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check. ## Severity and exploitation - 5.3 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`, from CNA (GitHub_M) - **CISA KEV:** Not listed. - **EPSS:** 0.0047, the 40th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days. ## Timeline - 31 Oct 2026, 15:09 UTC: First seen by agentprime - 31 Oct 2026, 15:09 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-rrw2-px9j-qffj) ## Sources - [GitHub Advisory Database: GHSA-rrw2-px9j-qffj](https://github.com/advisories/GHSA-rrw2-px9j-qffj) - [OSV: GHSA-rrw2-px9j-qffj](https://osv.dev/vulnerability/GHSA-rrw2-px9j-qffj) - - - - - - - - - - Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code. ## Check whether this affects you A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet. - With the agentprime MCP server (), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: - In a browser: reads your lockfile in the browser, never uploading it. - Whether it touches your code, with file and line: the Claude Code plugin, - As JSON: , or `POST https://api.agentprime.io/v1/match` with your packages () --- The web page: . Everything for agents: .