CVE-2019-8849: Github.com/apple/swift nio ssl SwiftNIO SSL Arbitrary Code Execution Vulnerability

CRITICAL
Advisory Identifier: GHSA-frg3-gpcx-968f
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CVSS 9.8
Published
Advisory Summary

CVE-2019-8849 is a CRITICAL (CVSS 9.8) swiftnio ssl arbitrary code execution vulnerability (General Security Weakness) affecting Github.com/apple/swift nio ssl libraries in the SwiftURL ecosystem. The issue involves swiftnio ssl arbitrary code execution vulnerability. Remediation is available by upgrading affected packages to version 2.4.1.

CVE-2019-8849 at a Glance

CVE Identifier CVE-2019-8849
GHSA Identifier GHSA-frg3-gpcx-968f
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification General Security Weakness
Affected Product Github.com/apple/swift nio ssl
Package Ecosystem SwiftURL
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2019-8849

To remediate this vulnerability, upgrade all affected Github.com/apple/swift nio ssl dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/apple/swift-nio-ssl fixed: 2.4.1 
Upgrade github.com/apple/swift-nio-ssl to 2.4.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/apple/swift-nio-ssl

How to Check if You Are Affected

To determine whether your application is affected by CVE-2019-8849, inspect your project dependencies for Github.com/apple/swift nio ssl:

inspect dependencies for github.com/apple/swift-nio-ssl

Analyze the terminal output to locate any version of Github.com/apple/swift nio ssl in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.4.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under General Security Weakness. In Github.com/apple/swift nio ssl, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2019-8849 Affected Github.com/apple/swift nio ssl Versions

1 component(s)
Fixed Versions:
2.4.1
Product / Package Ecosystem Affected Versions Fixed Version
github.com/apple/swift-nio-ssl
 SwiftURL
≥ 2.0.0
< 2.4.1
2.4.1

References

NVD — CVE-2019-8849 NVD
https://nvd.nist.gov/vuln/detail/CVE-2019-8849
Security Fix Commit FIX COMMIT
https://github.com/apple/swift-nio-ssl/commit/109faef770994e71b6bafcc015e2e96b88a4af8c
Github.com/apple/swift nio ssl Source Repository REPOSITORY
https://github.com/apple/swift-nio-ssl
Github.com/apple/swift nio ssl Release RELEASE
https://github.com/apple/swift-nio-ssl/releases/tag/2.4.1
Github.com/apple/swift nio ssl Security Information SECURITY
https://security.snyk.io/vuln/SNYK-COCOAPODS-SWIFTNIOSSL-8492737
support.apple.com/ht210772 WEB
https://support.apple.com/HT210772

Frequently Asked Questions

What is CVE-2019-8849?
CVE-2019-8849 is a security vulnerability in Github.com/apple/swift nio ssl involving SwiftNIO SSL arbitrary code execution vulnerability under General Security Weakness.
Which Github.com/apple/swift nio ssl versions are affected?
Affected versions include releases prior to 2.4.1 across affected packages: github.com/apple/swift-nio-ssl.
What version fixes CVE-2019-8849?
Upgrading to 2.4.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/apple/swift-nio-ssl affected?
Yes, github.com/apple/swift-nio-ssl is affected in releases prior to 2.4.1. Upgrade your dependency to 2.4.1 or later.
What is the CVSS score of CVE-2019-8849?
CVE-2019-8849 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2019-8849?
CVE-2019-8849 is classified under General Security Weakness.
How can I check SwiftURL dependencies for CVE-2019-8849?
Run the dependency tree command: 'inspect dependencies for github.com/apple/swift-nio-ssl'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-frg3-gpcx-968f",
  "modified" : "2025-08-04T14:23:36Z",
  "published" : "2022-05-24T17:04:41Z",
  "aliases" : [ "CVE-2019-8849" ],
  "summary" : "SwiftNIO SSL arbitrary code execution vulnerability",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "SwiftURL",
      "name" : "github.com/apple/swift-nio-ssl"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.4.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2019-8849"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apple/swift-nio-ssl/commit/109faef770994e71b6bafcc015e2e96b88a4af8c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apple/swift-nio-ssl"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apple/swift-nio-ssl/releases/tag/2.4.1"
  }, {
    "type" : "WEB",
    "url" : "https://security.snyk.io/vuln/SNYK-COCOAPODS-SWIFTNIOSSL-8492737"
  }, {
    "type" : "WEB",
    "url" : "https://support.apple.com/HT210772"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2023-06-06T01:55:25Z",
    "nvd_published_at" : "2019-12-18T18:15:00Z"
  }
}