CVE-2020-26231: October/cms Bypass Of Fix For CVE-2020-15247, Vulnerability

LOW
Advisory Identifier: GHSA-r89v-cgv7-3jhx
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CVSS 5.2
CWE-862
Published
Advisory Summary

CVE-2020-26231 is a LOW (CVSS 5.2) bypass of fix for cve-2020-15247, vulnerability (CWE-862: Missing Authorization) affecting October/cms libraries in the Packagist ecosystem. The issue involves bypass of fix for cve-2020-15247, twig sandbox escape. Remediation is available by upgrading affected packages to version 1.0.470.

CVE-2020-26231 at a Glance

CVE Identifier CVE-2020-26231
GHSA Identifier GHSA-r89v-cgv7-3jhx
Severity LOW
CVSS v3.1 Base Score 5.2
CWE Classification CWE-862: Missing Authorization
Affected Product October/cms
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 5.2

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

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required High (PR:H)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability Low (A:L)

How to Fix CVE-2020-26231

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

october/cms fixed: 1.0.470 
Upgrade october/cms to 1.0.470
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 october/cms

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-26231, inspect your project dependencies for October/cms:

inspect dependencies for october/cms

Analyze the terminal output to locate any version of October/cms in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.470), 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-862: Missing Authorization, where the product does not perform an authorization check when an actor attempts to access a resource or perform an action. In October/cms, 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

### Impact A bypass of CVE-2020-15247 (fixed in 1.0.469 and 1.1.0) was discovered that has the same impact as CVE-2020-15247: An authenticated backend user with the `cms.manage_pages`, `cms.manage_layouts`, or `cms.manage_partials` permissions who would **normally** not be permitted to provide PHP code to be executed by the CMS due to `cms.enableSafeMode` being enabled is able to write specific Twig code to escape the Twig sandbox and execute arbitrary PHP. This is not a problem for anyone that trusts their users with those permissions to normally write & manage PHP within the CMS by not having `cms.enableSafeMode` enabled, but would be a problem for anyone relying on `cms.enableSafeMode` to ensure that users with those permissions in production do not have access to write & execute arbitrary PHP. ### Patches Issue has been patched in Build 470 (v1.0.470) and v1.1.1. ### Workarounds Apply https://github.com/octobercms/october/commit/d34fb8ab51108495a9a651b841202d935f4e12f7 to your installation manually if unable to upgrade to Build 470 or v1.1.1. ### References Reported by [ka1n4t](https://github.com/ka1n4t) ### For more information If you have any questions or comments about this advisory: * Email us at [hello@octobercms.com](mailto:hello@octobercms.com) ### Threat assessment: <img width="1108" alt="Screen Shot 2020-10-10 at 1 21 13 PM" src="https://user-images.githubusercontent.com/7253840/95663316-7de28b80-0afb-11eb-999d-a6526cf78709.png">

CVE-2020-26231 Affected October/cms Versions

1 component(s)
Fixed Versions:
1.0.470
Product / Package Ecosystem Affected Versions Fixed Version
october/cms
 Packagist
≥ 1.0.469
< 1.0.470
All 1 versions
1.0.469
1.0.470

References

GitHub Advisory / Wiki ADVISORY
https://github.com/octobercms/october/security/advisories/GHSA-r89v-cgv7-3jhx
NVD — CVE-2020-26231 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-26231
Security Fix Commit FIX COMMIT
https://github.com/octobercms/october/commit/d34fb8ab51108495a9a651b841202d935f4e12f7
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-94vp-rmqv-5875

Frequently Asked Questions

What is CVE-2020-26231?
CVE-2020-26231 is a security vulnerability in October/cms involving Bypass of fix for CVE-2020-15247, Twig sandbox escape under CWE-862: Missing Authorization.
Which October/cms versions are affected?
Affected versions include releases prior to 1.0.470 across affected packages: october/cms.
What version fixes CVE-2020-26231?
Upgrading to 1.0.470 (or the latest patched release for your respective branch) resolves the vulnerability.
Is october/cms affected?
Yes, october/cms is affected in releases prior to 1.0.470. Upgrade your dependency to 1.0.470 or later.
What is the CVSS score of CVE-2020-26231?
CVE-2020-26231 has a CVSS v3.1 base score of 5.2 (LOW) with vector string CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L.
What CWE is associated with CVE-2020-26231?
CVE-2020-26231 is classified under CWE-862: Missing Authorization (The product does not perform an authorization check when an actor attempts to access a resource or perform an action.).
How can I check Packagist dependencies for CVE-2020-26231?
Run the dependency tree command: 'inspect dependencies for october/cms'. 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-r89v-cgv7-3jhx",
  "modified" : "2021-03-04T18:24:40Z",
  "published" : "2020-11-23T20:54:18Z",
  "aliases" : [ "CVE-2020-26231" ],
  "summary" : "Bypass of fix for CVE-2020-15247, Twig sandbox escape",
  "details" : "### Impact\nA bypass of CVE-2020-15247 (fixed in 1.0.469 and 1.1.0) was discovered that has the same impact as CVE-2020-15247:\n\nAn authenticated backend user with the `cms.manage_pages`, `cms.manage_layouts`, or `cms.manage_partials` permissions who would **normally** not be permitted to provide PHP code to be executed by the CMS due to `cms.enableSafeMode` being enabled is able to write specific Twig code to escape the Twig sandbox and execute arbitrary PHP.\n\nThis is not a problem for anyone that trusts their users with those permissions to normally write & manage PHP within the CMS by not having `cms.enableSafeMode` enabled, but would be a problem for anyone relying on `cms.enableSafeMode` to ensure that users with those permissions in production do not have access to write & execute arbitrary PHP.\n\n### Patches\nIssue has been patched in Build 470 (v1.0.470) and v1.1.1.\n\n### Workarounds\nApply https://github.com/octobercms/october/commit/d34fb8ab51108495a9a651b841202d935f4e12f7 to your installation manually if unable to upgrade to Build 470 or v1.1.1.\n\n### References\nReported by [ka1n4t](https://github.com/ka1n4t)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Email us at [hello@octobercms.com](mailto:hello@octobercms.com)\n\n### Threat assessment:\n<img width=\"1108\" alt=\"Screen Shot 2020-10-10 at 1 21 13 PM\" src=\"https://user-images.githubusercontent.com/7253840/95663316-7de28b80-0afb-11eb-999d-a6526cf78709.png\">",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "october/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.469"
      }, {
        "fixed" : "1.0.470"
      } ]
    } ],
    "versions" : [ "1.0.469" ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/octobercms/october/security/advisories/GHSA-r89v-cgv7-3jhx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-26231"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/octobercms/october/commit/d34fb8ab51108495a9a651b841202d935f4e12f7"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-94vp-rmqv-5875"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-862" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-11-23T20:53:51Z",
    "nvd_published_at" : null
  }
}