CVE-2025-58369

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

MEDIUM
5.3
CVSS Score
Published: September 5, 2025 at 09:59 PM UTC
Updated: October 1, 2026 at 04:10 PM UTC
1 product affected across 1 vendorFS2

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

fs2 is a compositional, streaming I/O library for Scala. Versions 3.12.2 and lower and 3.13.0-M1 through 3.13.0-M6 is 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 3.12.1 and 3.13.0-M7.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.5.13v < 3.12.2v < 3.13.0-M7
Affected range stops below 2.5.13, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.12.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 3.13.0-M7, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-400

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