CVE-2026-62996: Smarty/smarty Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rjhh-76wf-8xmw",
  "modified" : "2026-08-07T15:10:51Z",
  "published" : "2026-08-07T15:10:51Z",
  "aliases" : [ "CVE-2026-62996" ],
  "summary" : "Smarty Security stream restriction bypass through stream: resource",
  "details" : "`smarty/smarty` version `5.8.0` can read local files through PHP stream wrappers even when Smarty Security is enabled and all streams are disabled with `Security::$streams = null`.\n\nThe bypass uses Smarty's built-in `stream:` resource type. A template such as:\n\n```smarty\n{include file=\"stream:php://filter/read=convert.base64-encode/resource=/tmp/secret.tpl\"}\n```\n\nis handled as Smarty resource type `stream`, so the security check that would normally reject the underlying `php` wrapper is not applied. `StreamPlugin` then opens the nested `php://filter/...` URI directly.\n\nFor comparison, the direct resource:\n\n```smarty\n{include file=\"php://filter/read=convert.base64-encode/resource=/tmp/secret.tpl\"}\n```\n\nis blocked with `stream 'php' not allowed by security setting`.\n\nAffected package:\n\n- Ecosystem: Packagist / Composer\n- Package: `smarty/smarty`\n- Confirmed affected version: `5.8.0`\n- Confirmed source reference from Composer lock: `78d259d3b971c59a0cd719c270cc5cbb740c36a7`\n- Current stable version on Packagist at review time: `v5.8.0`\n- Packagist usage at review time: 41,113,855 total downloads and 840,604 monthly downloads\n\nRelevant code paths:\n\n- `Smarty\\Resource\\BasePlugin::load(...)`\n- `Smarty\\Resource\\StreamPlugin::getContent(...)`\n- `Smarty\\Security::isTrustedStream(...)`\n\n`BasePlugin::load()` maps the built-in resource name `stream` directly to `StreamPlugin` before the code path that checks PHP stream wrappers with `stream_get_wrappers()` and `Security::isTrustedStream($type)`. `StreamPlugin::getContent()` later calls `fopen($filepath, 'r+')` on the nested URI when the resource name contains `://`.\n\nPreconditions:\n\nAn application must render templates that are not fully trusted while relying on Smarty Security to restrict local files and PHP stream wrappers. The PoC sets:\n\n```php\n$smarty->enableSecurity();\n$smarty->security_policy->streams = null;\n```\n\nLocal reproduction:\n\nThe PoC creates a disposable template directory and a separate outside directory. It enables Smarty Security, disables all streams, and then compares three includes:\n\n1. `../outside/secret.tpl` to confirm the ordinary trusted-directory boundary is enforced.\n2. `php://filter/...` to confirm direct PHP streams are blocked by `Security::$streams = null`.\n3. `stream:php://filter/...` to show the built-in `stream:` resource bypasses the same restriction and reads the outside file.\n\nRun:\n\n```shell\nphp -d display_errors=1 poc.php\n```\n\nObserved sanitized output:\n\n```text\npackage=smarty/smarty\ninstalled_version=v5.8.0\ntemplate_dir=<tmp>/templates\noutside_template=<tmp>/outside/secret.tpl\nplain_dotdot_include=BLOCKED:Smarty\\Exception:Smarty Security: not trusted file path '<tmp>/outside/secret.tpl'\ndirect_php_filter_include=BLOCKED:Smarty\\Exception:stream 'php' not allowed by security setting\nstream_php_filter_include=OK:U01BUlRZX1NUUkVBTV9XUkFQUEVSX1NFQ1VSSVRZX0VTQ0FQRQ==\nexpected_base64=U01BUlRZX1NUUkVBTV9XUkFQUEVSX1NFQ1VSSVRZX0VTQ0FQRQ==\n```\n\nThe `plain_dotdot_include` line shows the directory boundary is enforced for ordinary traversal. The `direct_php_filter_include` line shows the same policy rejects `php://filter` when used directly. The `stream_php_filter_include` line shows that wrapping the same URI in Smarty's `stream:` resource bypasses that restriction and reads the outside file.\n\nImpact:\n\nA template author can bypass Smarty Security stream restrictions and read local files that are readable by the PHP process. With `php://filter`, file contents can be base64 encoded and rendered back through the template. This bypasses both the intended `Security::$streams = null` restriction and the normal trusted-template-directory check that blocks `../` traversal.\n\nDuplicate checks:\n\n- OSV query for `Packagist/smarty/smarty` version `5.8.0` returned no vulnerabilities.\n- GitHub advisory query for `ecosystem=composer` and `affects=smarty/smarty` returned historical Smarty advisories, including sandbox escapes, PHP code injection, XSS, and older path traversal issues. The listed path traversal advisories affect older versions and do not describe this current `stream:php://filter` resource-wrapper bypass in 5.8.0.\n- GitHub issue search in `smarty-php/smarty` for `stream:php://filter` returned zero results.\n- Public searches for `Smarty StreamPlugin php://filter` and `smarty/smarty isTrustedStream stream:` did not identify a clear public duplicate during triage.\n\nSuggested remediation:\n\nWhen resolving the built-in `stream:` resource, parse and validate the nested URI scheme before opening it. For example, `stream:php://filter/...` should call `Security::isTrustedStream('php')`, and `Security::$streams = null` should block the resource before `StreamPlugin::getContent()` reaches `fopen()`.\n\nIt would also be safer for `StreamPlugin` to reject nested stream wrappers by default unless the underlying wrapper is explicitly allowed by the active security policy.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "smarty/smarty"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "5.0.0"
      }, {
        "fixed" : "5.8.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/security/advisories/GHSA-rjhh-76wf-8xmw"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/pull/1195"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/commit/3c9f77a2e06ce319ae0092496af32cc8f3adc52e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/smarty-php/smarty"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/smarty-php/smarty/releases/tag/v5.8.4"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-07T15:10:51Z",
    "nvd_published_at" : null
  }
}