GHSA-8v8v-g73j-492j
Symfony's JsonPath Evaluates Attacker-Controlled Regular Expressions in match()/search() Without Limits — ReDoS
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Packagist | symfony/json-path | >= 7.3.0, < 7.4.12 | 7.4.12 |
| Packagist | symfony/json-path | >= 8.0.0, < 8.0.12 | 8.0.12 |
| Packagist | symfony/symfony | >= 7.3.0, < 7.4.12 | 7.4.12 |
| Packagist | symfony/symfony | >= 8.0.0, < 8.0.12 | 8.0.12 |
Details
As written in the advisory (Markdown source, shown as plain text).
### Description
The `JsonPath` component's `match()` and `search()` filter functions compile a caller-supplied pattern straight into `preg_match()`:
```php
'match' => @preg_match(\sprintf('/^%s$/u', $this->transformJsonPathRegex($argList[1])), $value),
'search' => @preg_match("/{$this->transformJsonPathRegex($argList[1])}/u", $value),
```
`transformJsonPathRegex()` only performs cosmetic escaping: there is no length cap, no restriction to the RFC 9485 i-regexp subset, and no bound on backtracking. An application that evaluates an attacker-influenced JSONPath expression server-side (e.g. one taken from a query parameter or API field and passed to `JsonCrawler`) can therefore be made to run a catastrophic-backtracking pattern such as `$[?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.
### Conditions for exploitation
An application that evaluates an attacker-influenced JSONPath expression containing a `match()` / `search()` filter against any non-trivial JSON input.
### Resolution
`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.
The patch for this issue is available [here](https://github.com/symfony/symfony/commit/1ac2d47418ec23066112db1e6ca35be6fe123d14) for branch 7.4.
### Credits
Symfony would like to thank Himanshu Anand for reporting the issue and Alexandre Daubois for providing the fix.
References
External links from the advisory. They lead to third-party sites.
- https://github.com/symfony/symfony/security/advisories/GHSA-8v8v-g73j-492j
- https://github.com/symfony/symfony/commit/1ac2d47418ec23066112db1e6ca35be6fe123d14
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/json-path/CVE-2026-45756.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45756.yaml
- https://github.com/symfony/symfony
- https://symfony.com/cve-2026-45756