CVE-2020-15249: October/backend Cross-Site Scripting Vulnerability

LOW
Advisory Identifier: GHSA-fx3v-553x-3c4q
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CVSS 2.8
CWE-79
Published
Advisory Summary

CVE-2020-15249 is a LOW (CVSS 2.8) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting October/backend libraries in the Packagist ecosystem. The issue involves stored xss by authenticated backend user with access to upload files. Remediation is available by upgrading affected packages to version 1.0.469.

CVE-2020-15249 at a Glance

CVE Identifier CVE-2020-15249
GHSA Identifier GHSA-fx3v-553x-3c4q
Severity LOW
CVSS v3.1 Base Score 2.8
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product October/backend
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 2.8

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

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

How to Fix CVE-2020-15249

To remediate this vulnerability, upgrade all affected October/backend 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/backend fixed: 1.0.469 
Upgrade october/backend to 1.0.469
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/backend

How to Check if You Are Affected

To determine whether your application is affected by CVE-2020-15249, inspect your project dependencies for October/backend:

inspect dependencies for october/backend

Analyze the terminal output to locate any version of October/backend in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.469), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In October/backend, 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 Backend users with access to upload files were permitted to upload SVG files without any sanitization applied to the uploaded files. Since SVG files support being parsed as HTML by browsers, this means that they could theoretically upload Javascript that would be executed on a path under the website's domain (i.e. /storage/app/media/evil.svg), but they would have to convince their target to visit that location directly in the target's browser as the backend does not display SVGs inline anywhere, SVGs are only displayed as image resources in the backend and are thus unable to be executed. ### Patches Issue has been patched in Build 469 (v1.0.469) & v1.1.0. ### Workarounds Apply https://github.com/octobercms/library/commit/80aab47f044a2660aa352450f55137598f362aa4 to your installation manually if unable to upgrade to Build 469 or v1.1.0. ### References Reported by [Hoan Hoang](https://github.com/hoanhp) ### 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="1107" alt="Screen Shot 2020-10-10 at 1 47 49 PM" src="https://user-images.githubusercontent.com/7253840/95663787-378f2b80-0aff-11eb-8dfc-b97d162939da.png">

CVE-2020-15249 Affected October/backend Versions

1 component(s)
Fixed Versions:
1.0.469
Product / Package Ecosystem Affected Versions Fixed Version
october/backend
 Packagist
≥ 1.0.319
< 1.0.469
1.0.469

References

GitHub Advisory / Wiki ADVISORY
https://github.com/octobercms/october/security/advisories/GHSA-fx3v-553x-3c4q
NVD — CVE-2020-15249 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-15249
Security Fix Commit FIX COMMIT
https://github.com/octobercms/library/commit/80aab47f044a2660aa352450f55137598f362aa4

Frequently Asked Questions

What is CVE-2020-15249?
CVE-2020-15249 is a security vulnerability in October/backend involving Stored XSS by authenticated backend user with access to upload files under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which October/backend versions are affected?
Affected versions include releases prior to 1.0.469 across affected packages: october/backend.
What version fixes CVE-2020-15249?
Upgrading to 1.0.469 (or the latest patched release for your respective branch) resolves the vulnerability.
Is october/backend affected?
Yes, october/backend is affected in releases prior to 1.0.469. Upgrade your dependency to 1.0.469 or later.
What is the CVSS score of CVE-2020-15249?
CVE-2020-15249 has a CVSS v3.1 base score of 2.8 (LOW) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2020-15249?
CVE-2020-15249 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check Packagist dependencies for CVE-2020-15249?
Run the dependency tree command: 'inspect dependencies for october/backend'. 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-fx3v-553x-3c4q",
  "modified" : "2021-03-04T18:24:54Z",
  "published" : "2020-11-23T19:47:59Z",
  "aliases" : [ "CVE-2020-15249" ],
  "summary" : "Stored XSS by authenticated backend user with access to upload files",
  "details" : "### Impact\nBackend users with access to upload files were permitted to upload SVG files without any sanitization applied to the uploaded files. Since SVG files support being parsed as HTML by browsers, this means that they could theoretically upload Javascript that would be executed on a path under the website's domain (i.e. /storage/app/media/evil.svg), but they would have to convince their target to visit that location directly in the target's browser as the backend does not display SVGs inline anywhere, SVGs are only displayed as image resources in the backend and are thus unable to be executed.\n\n### Patches\nIssue has been patched in Build 469 (v1.0.469) & v1.1.0.\n\n### Workarounds\nApply https://github.com/octobercms/library/commit/80aab47f044a2660aa352450f55137598f362aa4 to your installation manually if unable to upgrade to Build 469 or v1.1.0.\n\n### References\nReported by [Hoan Hoang](https://github.com/hoanhp)\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=\"1107\" alt=\"Screen Shot 2020-10-10 at 1 47 49 PM\" src=\"https://user-images.githubusercontent.com/7253840/95663787-378f2b80-0aff-11eb-8dfc-b97d162939da.png\">",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "october/backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.319"
      }, {
        "fixed" : "1.0.469"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/octobercms/october/security/advisories/GHSA-fx3v-553x-3c4q"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-15249"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/octobercms/library/commit/80aab47f044a2660aa352450f55137598f362aa4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-11-23T19:47:07Z",
    "nvd_published_at" : null
  }
}