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SwiftNIO SSL arbitrary code execution vulnerability

Critical severity GitHub Reviewed Published May 24, 2022 to the GitHub Advisory Database • Updated Aug 5, 2025

Package

swift github.com/apple/swift-nio-ssl (Swift)

Affected versions

>= 2.0.0, < 2.4.1

Patched versions

2.4.1

Description

A SwiftNIO application using TLS may be able to execute arbitrary code. The issue was addressed by signaling that an executable stack is not required. This issue is fixed in SwiftNIO SSL 2.4.1.

References

Published by the National Vulnerability Database Dec 18, 2019
Published to the GitHub Advisory Database May 24, 2022
Reviewed Jun 6, 2023
Last updated Aug 5, 2025

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(68th percentile)

Weaknesses

No CWEs

CVE ID

CVE-2019-8849

GHSA ID

GHSA-frg3-gpcx-968f

Source code

Credits

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