CVE-2026-61823: Code16/sharp Cross-Site Scripting Vulnerability

HIGH
Advisory Identifier: GHSA-qxg3-46rw-79j8
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CVSS 7.3
CWE-79
Published
Advisory Summary

CVE-2026-61823 is a HIGH (CVSS 7.3) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Code16/sharp libraries in the Packagist ecosystem. The issue involves code16 sharp vulnerable to stored xss via iframe srcdoc attribute. Remediation is available by upgrading affected packages to version 9.22.5.

CVE-2026-61823 at a Glance

CVE Identifier CVE-2026-61823
GHSA Identifier GHSA-qxg3-46rw-79j8
Severity HIGH
CVSS v3.1 Base Score 7.3
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Code16/sharp
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 7.3

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

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

How to Fix CVE-2026-61823

To remediate this vulnerability, upgrade all affected Code16/sharp dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

code16/sharp fixed: 9.22.5 
Upgrade code16/sharp to 9.22.5
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 code16/sharp

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-61823, inspect your project dependencies for Code16/sharp:

inspect dependencies for code16/sharp

Analyze the terminal output to locate any version of Code16/sharp in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 9.22.5), 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 Code16/sharp, 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 Stored Cross-Site Scripting (XSS) vulnerability exists in the rich text editor due to improper sanitization of the srcdoc attribute on <iframe> elements. While the underlying Symfony HtmlSanitizer correctly HTML-encodes special characters inside the attribute value (e.g., converting <script> to &lt;script&gt;), the HTML specification mandates that browsers automatically decode HTML entities inside attribute values before processing them. As a result, any encoded JavaScript inside a srcdoc attribute is evaluated and executed as live HTML/JS in the context of the iframe when the page is rendered. An attacker with permissions to edit an Editor field can inject malicious scripts to target other users viewing the content. Potential impacts include: - Session Hijacking (stealing admin session cookies via document.cookie) - Account Takeover & Privilege Escalation (e.g., a low-privileged editor triggering actions as an Administrator) - Admin panel data theft ### Patches The vulnerability has been patched in version v9.22.5. The fix explicitly removes srcdoc from the list of allowed iframe attributes in `src/Utils/Sanitization/FormatsSanitizedValue.php`. ### Workarounds Users who cannot upgrade immediately can manually sanitize all content of editor fields to strip `srcdoc` attributes.

CVE-2026-61823 Affected Code16/sharp Versions

1 component(s)
Fixed Versions:
9.22.5
Product / Package Ecosystem Affected Versions Fixed Version
code16/sharp
 Packagist
< 9.22.5
9.22.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/code16/sharp/security/advisories/GHSA-qxg3-46rw-79j8
NVD — CVE-2026-61823 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-61823
Security Fix Commit FIX COMMIT
https://github.com/code16/sharp/commit/ec509a22c808a5bd9dfad6a0a85c92ce6f411e21
Code16/sharp Source Repository REPOSITORY
https://github.com/code16/sharp

Frequently Asked Questions

What is CVE-2026-61823?
CVE-2026-61823 is a security vulnerability in Code16/sharp involving code16 Sharp vulnerable to stored XSS via iframe srcdoc Attribute under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Code16/sharp versions are affected?
Affected versions include releases prior to 9.22.5 across affected packages: code16/sharp.
What version fixes CVE-2026-61823?
Upgrading to 9.22.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is code16/sharp affected?
Yes, code16/sharp is affected in releases prior to 9.22.5. Upgrade your dependency to 9.22.5 or later.
What is the CVSS score of CVE-2026-61823?
CVE-2026-61823 has a CVSS v3.1 base score of 7.3 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N.
What CWE is associated with CVE-2026-61823?
CVE-2026-61823 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-2026-61823?
Run the dependency tree command: 'inspect dependencies for code16/sharp'. 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-qxg3-46rw-79j8",
  "modified" : "2026-09-25T15:02:11Z",
  "published" : "2026-09-25T15:02:11Z",
  "aliases" : [ "CVE-2026-61823" ],
  "summary" : "code16 Sharp vulnerable to stored XSS via iframe srcdoc Attribute",
  "details" : "### Impact\nA Stored Cross-Site Scripting (XSS) vulnerability exists in the rich text editor due to improper sanitization of the srcdoc attribute on <iframe> elements.\n\nWhile the underlying Symfony HtmlSanitizer correctly HTML-encodes special characters inside the attribute value (e.g., converting <script> to &lt;script&gt;), the HTML specification mandates that browsers automatically decode HTML entities inside attribute values before processing them. As a result, any encoded JavaScript inside a srcdoc attribute is evaluated and executed as live HTML/JS in the context of the iframe when the page is rendered.\n\nAn attacker with permissions to edit an Editor field can inject malicious scripts to target other users viewing the content. Potential impacts include:\n\n- Session Hijacking (stealing admin session cookies via document.cookie)\n- Account Takeover & Privilege Escalation (e.g., a low-privileged editor triggering actions as an Administrator)\n- Admin panel data theft\n\n### Patches\nThe vulnerability has been patched in version v9.22.5.\n\nThe fix explicitly removes srcdoc from the list of allowed iframe attributes in `src/Utils/Sanitization/FormatsSanitizedValue.php`.\n\n### Workarounds\nUsers who cannot upgrade immediately can manually sanitize all content of editor fields to strip `srcdoc` attributes.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "code16/sharp"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "9.22.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/code16/sharp/security/advisories/GHSA-qxg3-46rw-79j8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-61823"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/code16/sharp/commit/ec509a22c808a5bd9dfad6a0a85c92ce6f411e21"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/code16/sharp"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-25T15:02:11Z",
    "nvd_published_at" : "2026-09-24T19:17:15Z"
  }
}