CVE-2026-54720: Silverstripe Framework Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-gvrw-qqp5-jgc5
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CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2026-54720 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Silverstripe Framework libraries in the Packagist ecosystem. The issue involves possible xss attack through media embed. Remediation is available by upgrading affected packages to version 6.2.2.

CVE-2026-54720 at a Glance

CVE Identifier CVE-2026-54720
GHSA Identifier GHSA-gvrw-qqp5-jgc5
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Silverstripe Framework
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 5.4

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:R/S:U/C:L/I:L/A:N).

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

How to Fix CVE-2026-54720

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

silverstripe/framework fixed: 6.2.2 
Upgrade silverstripe/framework to 6.2.2
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 silverstripe/framework

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-54720, inspect your project dependencies for Silverstripe Framework:

inspect dependencies for silverstripe/framework

Analyze the terminal output to locate any version of Silverstripe Framework in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.2.2), 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 Silverstripe Framework, 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 The "Insert media from web" functionality in the CMS is vulnerable to XSS from a specially crafted embed. ### Reported by Jack Wallace from Bastion Security

CVE-2026-54720 Affected Silverstripe Framework Versions

1 component(s)
Fixed Versions:
6.2.2
Product / Package Ecosystem Affected Versions Fixed Version
silverstripe/framework
 Packagist
< 6.2.2
6.2.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/silverstripe/silverstripe-framework/security/advisories/GHSA-gvrw-qqp5-jgc5
NVD — CVE-2026-54720 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54720
Silverstripe Framework Source Repository REPOSITORY
https://github.com/silverstripe/silverstripe-framework/pull/11993
Security Fix Commit FIX COMMIT
https://github.com/silverstripe/silverstripe-framework/commit/1bcb02adfc365c6436dc26ab2f6dd32d97f3979b
Silverstripe Framework Source Repository REPOSITORY
https://github.com/FriendsOfPHP/security-advisories/blob/master/silverstripe/framework/CVE-2026-54720.yaml
Silverstripe Framework Source Repository REPOSITORY
https://github.com/silverstripe/silverstripe-framework
Silverstripe Framework Release RELEASE
https://github.com/silverstripe/silverstripe-framework/releases/tag/6.2.2
Silverstripe Framework Release RELEASE
https://www.silverstripe.org/download/security-releases/cve-2026-54720

Frequently Asked Questions

What is CVE-2026-54720?
CVE-2026-54720 is a security vulnerability in Silverstripe Framework involving Possible XSS attack through media embed under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Silverstripe Framework versions are affected?
Affected versions include releases prior to 6.2.2 across affected packages: silverstripe/framework.
What version fixes CVE-2026-54720?
Upgrading to 6.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is silverstripe/framework affected?
Yes, silverstripe/framework is affected in releases prior to 6.2.2. Upgrade your dependency to 6.2.2 or later.
What is the CVSS score of CVE-2026-54720?
CVE-2026-54720 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-54720?
CVE-2026-54720 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-2026-54720?
Run the dependency tree command: 'inspect dependencies for silverstripe/framework'. 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-gvrw-qqp5-jgc5",
  "modified" : "2026-08-27T16:49:48Z",
  "published" : "2026-08-27T16:49:47Z",
  "aliases" : [ "CVE-2026-54720" ],
  "summary" : "Silverstripe Framework: Possible XSS attack through media embed",
  "details" : "### Impact\nThe \"Insert media from web\" functionality in the CMS is vulnerable to XSS from a specially crafted embed.\n\n### Reported by\nJack Wallace from Bastion Security",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "silverstripe/framework"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "6.2.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/silverstripe/silverstripe-framework/security/advisories/GHSA-gvrw-qqp5-jgc5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-54720"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/silverstripe/silverstripe-framework/pull/11993"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/silverstripe/silverstripe-framework/commit/1bcb02adfc365c6436dc26ab2f6dd32d97f3979b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/silverstripe/framework/CVE-2026-54720.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/silverstripe/silverstripe-framework"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/silverstripe/silverstripe-framework/releases/tag/6.2.2"
  }, {
    "type" : "WEB",
    "url" : "https://www.silverstripe.org/download/security-releases/cve-2026-54720"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-27T16:49:47Z",
    "nvd_published_at" : "2026-07-01T21:17:03Z"
  }
}