CVE-2020-17952: Topthink/think Code Injection Vulnerability

CRITICAL
Advisory Identifier: GHSA-ch3r-vp46-8g22
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CVSS 9.8
CWE-74
Published
Advisory Summary

CVE-2020-17952 is a CRITICAL (CVSS 9.8) code injection vulnerability (CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')) affecting Topthink/think libraries in the Packagist ecosystem. The issue involves code injection in topthink/think. Remediation is available in the latest vendor maintenance releases.

CVE-2020-17952 at a Glance

CVE Identifier CVE-2020-17952
GHSA Identifier GHSA-ch3r-vp46-8g22
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Affected Product Topthink/think
Package Ecosystem Packagist
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-2020-17952

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

topthink/think fixed: Latest secure release 
Upgrade topthink/think to Latest secure release
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 topthink/think

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-17952, inspect your project dependencies for Topthink/think:

inspect dependencies for topthink/think

Analyze the terminal output to locate any version of Topthink/think in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), 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-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection'), where the product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. In Topthink/think, 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 remote code execution (RCE) vulnerability in /library/think/App.php of Twothink v2.0 allows attackers to execute arbitrary PHP code.

CVE-2020-17952 Affected Topthink/think Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
topthink/think
 Packagist
≤ 6.0.9

References

NVD — CVE-2020-17952 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-17952
Topthink/think Source Repository REPOSITORY
https://github.com/twothink/twothink/issues/1
Topthink/think Source Repository REPOSITORY
https://github.com/twothink/twothink

Frequently Asked Questions

What is CVE-2020-17952?
CVE-2020-17952 is a security vulnerability in Topthink/think involving Code injection in topthink/think under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection').
Which Topthink/think versions are affected?
Affected versions include releases prior to current release patches across affected packages: topthink/think.
What version fixes CVE-2020-17952?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is topthink/think affected?
Yes, topthink/think is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What is the CVSS score of CVE-2020-17952?
CVE-2020-17952 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-2020-17952?
CVE-2020-17952 is classified under CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') (The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.).
How can I check Packagist dependencies for CVE-2020-17952?
Run the dependency tree command: 'inspect dependencies for topthink/think'. 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-ch3r-vp46-8g22",
  "modified" : "2021-08-31T21:00:31Z",
  "published" : "2021-08-09T20:39:52Z",
  "aliases" : [ "CVE-2020-17952" ],
  "summary" : "Code injection in topthink/think",
  "details" : "A remote code execution (RCE) vulnerability in /library/think/App.php of Twothink v2.0 allows attackers to execute arbitrary PHP code.",
  "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" : "Packagist",
      "name" : "topthink/think"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "6.0.9"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-17952"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/twothink/twothink/issues/1"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/twothink/twothink"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-74" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-02T21:43:12Z",
    "nvd_published_at" : "2021-07-26T20:15:00Z"
  }
}