CVE-2020-16017: CefSharp.Common Use After Free Vulnerability

HIGH
Advisory Identifier: GHSA-gvqv-779r-4jgp
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CWE-416
Published
Advisory Summary

CVE-2020-16017 is a HIGH use after free vulnerability (CWE-416: Use After Free) affecting CefSharp.Common libraries in the NuGet ecosystem. The issue involves use after free in cefsharp. Remediation is available by upgrading affected packages to version 86.0.241.

CVE-2020-16017 at a Glance

CVE Identifier CVE-2020-16017
GHSA Identifier GHSA-gvqv-779r-4jgp
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-416: Use After Free
Affected Product CefSharp.Common
Package Ecosystem NuGet
Published Date
Last Updated

How to Fix CVE-2020-16017

To remediate this vulnerability, upgrade all affected CefSharp.Common dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

CefSharp.Common fixed: 86.0.241 
Upgrade CefSharp.Common to 86.0.241
CefSharp.Wpf fixed: 86.0.241 
Upgrade CefSharp.Wpf to 86.0.241
CefSharp.WinForms fixed: 86.0.241 
Upgrade CefSharp.WinForms to 86.0.241
CefSharp.Wpf.HwndHost fixed: 86.0.241 
Upgrade CefSharp.Wpf.HwndHost to 86.0.241
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 CefSharp.Common

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-16017, inspect your project dependencies for CefSharp.Common:

inspect dependencies for CefSharp.Common

Analyze the terminal output to locate any version of CefSharp.Common in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 86.0.241), 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 CWE-416: Use After Free, where the product reuses or references memory after it has been freed. at some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. In CefSharp.Common, 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

CVE-2020-16017: Use after free in site isolation - https://chromereleases.googleblog.com/2020/11/stable-channel-update-for-desktop_11.html - https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-16017 Google is aware of reports that exploits for CVE-2020-16013 and CVE-2020-16017 exist in the wild. There is currently little to no public information on the issue other than it has been flagged as `High` severity.

CVE-2020-16017 Affected CefSharp.Common Versions

4 component(s)
Fixed Versions:
86.0.241
Product / Package Ecosystem Affected Versions Fixed Version
CefSharp.Common
nuget/CefSharp.Common
NuGet
< 86.0.241
86.0.241
CefSharp.Wpf
nuget/CefSharp.Wpf
NuGet
< 86.0.241
86.0.241
CefSharp.WinForms
nuget/CefSharp.WinForms
NuGet
< 86.0.241
86.0.241
CefSharp.Wpf.HwndHost
nuget/CefSharp.Wpf.HwndHost
NuGet
< 86.0.241
86.0.241

References

GitHub Advisory / Wiki ADVISORY
https://github.com/cefsharp/CefSharp/security/advisories/GHSA-gvqv-779r-4jgp
NVD — CVE-2020-16017 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-16017
chromereleases.googleblog.com/2020/11/stable-chan... WEB
https://chromereleases.googleblog.com/2020/11/stable-channel-update-for-desktop_11.html
crbug.com/1146709 WEB
https://crbug.com/1146709

Frequently Asked Questions

What is CVE-2020-16017?
CVE-2020-16017 is a security vulnerability in CefSharp.Common involving Use after free in CefSharp under CWE-416: Use After Free.
Which CefSharp.Common versions are affected?
Affected versions include releases prior to 86.0.241 across affected packages: CefSharp.Common, CefSharp.Wpf, CefSharp.WinForms, CefSharp.Wpf.HwndHost.
What version fixes CVE-2020-16017?
Upgrading to 86.0.241 (or the latest patched release for your respective branch) resolves the vulnerability.
Is CefSharp.Common affected?
Yes, CefSharp.Common is affected in releases prior to 86.0.241. Upgrade your dependency to 86.0.241 or later.
Is CefSharp.Wpf affected?
Yes, CefSharp.Wpf is affected in releases prior to 86.0.241. Upgrade your dependency to 86.0.241 or later.
What CWE is associated with CVE-2020-16017?
CVE-2020-16017 is classified under CWE-416: Use After Free (The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.).
How can I check NuGet dependencies for CVE-2020-16017?
Run the dependency tree command: 'inspect dependencies for CefSharp.Common'. 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-gvqv-779r-4jgp",
  "modified" : "2020-11-27T20:06:27Z",
  "published" : "2020-11-27T20:13:05Z",
  "aliases" : [ "CVE-2020-16017" ],
  "summary" : "Use after free in CefSharp",
  "details" : "CVE-2020-16017: Use after free in site isolation\n\n- https://chromereleases.googleblog.com/2020/11/stable-channel-update-for-desktop_11.html\n- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-16017\n\nGoogle is aware of reports that exploits for CVE-2020-16013 and CVE-2020-16017 exist in the wild.\n\nThere is currently little to no public information on the issue other than it has been flagged as `High` severity.",
  "severity" : [ ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CefSharp.Common"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "86.0.241"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CefSharp.Wpf"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "86.0.241"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CefSharp.WinForms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "86.0.241"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "CefSharp.Wpf.HwndHost"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "86.0.241"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/cefsharp/CefSharp/security/advisories/GHSA-gvqv-779r-4jgp"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-16017"
  }, {
    "type" : "WEB",
    "url" : "https://chromereleases.googleblog.com/2020/11/stable-channel-update-for-desktop_11.html"
  }, {
    "type" : "WEB",
    "url" : "https://crbug.com/1146709"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-11-27T20:06:27Z",
    "nvd_published_at" : "2021-01-08T19:15:00Z"
  }
}