GHSA-53H4-8RC4-F539

Vulnerability from github – Published: 2026-06-23 21:54 – Updated: 2026-06-23 21:54
VLAI
Summary
Slim has Reflected XSS in the HtmlErrorRenderer
Details

Impact

If an application uses HttpException::setTitle() and/or setDescription() to include untrusted/request-derived data in the error title or description (e.g. "No products found matching '{$query}'."), an attacker could inject arbitrary HTML/JavaScript that executes in the victim's browser when they encounter an HTML error page generated by Slim.

The vulnerability is present even with displayErrorDetails = false as the unescaped title and description are rendered on this error path.

Built-in exceptions (HttpNotFoundException, HttpBadRequestException, etc.) ship plain-text defaults, so a vanilla Slim app with no user code is not exploitable. Only applications that feed untrusted data into setTitle() and/or setDescription() are affected.

Patches

The issue is fixed in 4.15.2.

Workarounds

Without upgrading, applications can:

  • Avoid passing untrusted/request-derived data into HttpException::setTitle() and setDescription(). Use static, plain-text error copy instead.
  • Register a custom error renderer (an ErrorRendererInterface implementation, or a subclass of HtmlErrorRenderer that escapes the title and description) for the HTML media type.

Acknowledgments

Slim is grateful to and thanks GitHub user 0xEr3n for reporting this issue.

Resources

  • CWE-79: https://cwe.mitre.org/data/definitions/79.html
Severity
6.1 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Show details on source website
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.15.1"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "slim/slim"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.4.0"
            },
            {
              "fixed": "4.15.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-48157"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-23T21:54:06Z",
    "nvd_published_at": "2026-06-15T22:16:17Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nIf an application uses `HttpException::setTitle()` and/or `setDescription()` to include untrusted/request-derived data in the error title or description (e.g. `\"No products found matching \u0027{$query}\u0027.\"`), an attacker could inject arbitrary HTML/JavaScript that executes in the victim\u0027s browser when they encounter an HTML error page generated by Slim.\n\nThe vulnerability is present even with `displayErrorDetails = false` as the unescaped title and description are rendered on this error path.\n\nBuilt-in exceptions (`HttpNotFoundException`, `HttpBadRequestException`, etc.) ship plain-text defaults, so a vanilla Slim app with no user code is not exploitable. Only applications that feed untrusted data into `setTitle()` and/or `setDescription()` are affected.\n\n### Patches\n\nThe issue is fixed in 4.15.2.\n\n### Workarounds\n\nWithout upgrading, applications can:\n\n- Avoid passing untrusted/request-derived data into `HttpException::setTitle()` and `setDescription()`. Use static, plain-text error copy instead.\n- Register a custom error renderer (an `ErrorRendererInterface` implementation, or a subclass of `HtmlErrorRenderer` that escapes the title and description) for the HTML media type.\n\n### Acknowledgments\n\nSlim is grateful to and thanks GitHub user [0xEr3n](https://github.com/0xEr3n) for reporting this issue.\n\n### Resources\n\n- CWE-79: https://cwe.mitre.org/data/definitions/79.html",
  "id": "GHSA-53h4-8rc4-f539",
  "modified": "2026-06-23T21:54:06Z",
  "published": "2026-06-23T21:54:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/slimphp/Slim/security/advisories/GHSA-53h4-8rc4-f539"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-48157"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/slimphp/Slim"
    },
    {
      "type": "WEB",
      "url": "https://github.com/slimphp/Slim/releases/tag/4.15.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Slim has Reflected XSS in the HtmlErrorRenderer"
}


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