CVE-2026-45756: Symfony/json path Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8v8v-g73j-492j",
  "modified" : "2026-05-28T17:34:55Z",
  "published" : "2026-05-28T17:34:55Z",
  "aliases" : [ "CVE-2026-45756" ],
  "summary" : "Symfony's JsonPath Evaluates Attacker-Controlled Regular Expressions in match()/search() Without Limits — ReDoS",
  "details" : "### Description\n\nThe `JsonPath` component's `match()` and `search()` filter functions compile a caller-supplied pattern straight into `preg_match()`:\n\n```php\n'match'  => @preg_match(\\sprintf('/^%s$/u', $this->transformJsonPathRegex($argList[1])), $value),\n'search' => @preg_match(\"/{$this->transformJsonPathRegex($argList[1])}/u\", $value),\n```\n\n`transformJsonPathRegex()` only performs cosmetic escaping: there is no length cap, no restriction to the RFC 9485 i-regexp subset, and no bound on backtracking. An application that evaluates an attacker-influenced JSONPath expression server-side (e.g. one taken from a query parameter or API field and passed to `JsonCrawler`) can therefore be made to run a catastrophic-backtracking pattern such as `$[?search(@, \"(a+)+$\")]`. Evaluated against a moderately sized document, this pins a CPU core for seconds per request, so a handful of concurrent requests exhausts the worker pool: a denial of service. Because the `preg_match()` calls are prefixed with `@`, the PCRE backtrack-limit errors that would otherwise surface are suppressed, leaving no log trace.\n\n### Conditions for exploitation\n\nAn application that evaluates an attacker-influenced JSONPath expression containing a `match()` / `search()` filter against any non-trivial JSON input.\n\n### Resolution\n\n`JsonCrawler` runs the `preg_match()` calls through a helper that lowers `pcre.backtrack_limit` to 10000 for the duration of the call (restoring the previous value afterwards), so a pathological pattern fails fast instead of stalling the worker.\n\nThe patch for this issue is available [here](https://github.com/symfony/symfony/commit/1ac2d47418ec23066112db1e6ca35be6fe123d14) for branch 7.4.\n\n### Credits\n\nSymfony would like to thank Himanshu Anand for reporting the issue and Alexandre Daubois for providing the fix.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/json-path"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.3.0"
      }, {
        "fixed" : "7.4.12"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/json-path"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.0.12"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/symfony"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.3.0"
      }, {
        "fixed" : "7.4.12"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "symfony/symfony"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "8.0.0"
      }, {
        "fixed" : "8.0.12"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/symfony/symfony/security/advisories/GHSA-8v8v-g73j-492j"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/symfony/symfony/commit/1ac2d47418ec23066112db1e6ca35be6fe123d14"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/json-path/CVE-2026-45756.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45756.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/symfony/symfony"
  }, {
    "type" : "WEB",
    "url" : "https://symfony.com/cve-2026-45756"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1333", "CWE-400" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-28T17:34:55Z",
    "nvd_published_at" : null
  }
}