CVE-2026-45756

CVE-2026-45756 is a low-severity uncontrolled resource consumption vulnerability in symfony/json-path (composer), affecting versions >= 7.3.0, < 7.4.12. It is fixed in 7.4.12, 8.0.12.

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Summary

Symfony's JsonPath Evaluates Attacker-Controlled Regular Expressions in match()/search() Without Limits, ReDoS

Description

The JsonPath component's match() and search() filter functions compile a caller-supplied pattern straight into preg_match():

'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 for branch 7.4.

Credits

Symfony would like to thank Himanshu Anand for reporting the issue and Alexandre Daubois for providing the fix.

Impact

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

Affected versions

symfony/json-path (>= 7.3.0, < 7.4.12) symfony/json-path (>= 8.0.0, < 8.0.12) symfony/symfony (>= 7.3.0, < 7.4.12) symfony/symfony (>= 8.0.0, < 8.0.12)

Security releases

symfony/json-path → 7.4.12 (composer) symfony/json-path → 8.0.12 (composer) symfony/symfony → 7.4.12 (composer) symfony/symfony → 8.0.12 (composer)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

symfony/json-path to 7.4.12 or later; symfony/json-path to 8.0.12 or later; symfony/symfony to 7.4.12 or later; symfony/symfony to 8.0.12 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

  1. What is CVE-2026-45756? CVE-2026-45756 is a low-severity uncontrolled resource consumption vulnerability in symfony/json-path (composer), affecting versions >= 7.3.0, < 7.4.12. It is fixed in 7.4.12, 8.0.12. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
  2. Which packages are affected by CVE-2026-45756?
    • symfony/json-path (composer) (versions >= 7.3.0, < 7.4.12)
    • symfony/symfony (composer) (versions >= 7.3.0, < 7.4.12)
  3. Is there a fix for CVE-2026-45756? Yes. CVE-2026-45756 is fixed in 7.4.12, 8.0.12. Upgrade to this version or later.
  4. Is CVE-2026-45756 exploitable, and should I be worried? Whether CVE-2026-45756 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
  5. What actually determines whether CVE-2026-45756 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
  6. How do I fix CVE-2026-45756?
    • Upgrade symfony/json-path to 7.4.12 or later
    • Upgrade symfony/json-path to 8.0.12 or later
    • Upgrade symfony/symfony to 7.4.12 or later
    • Upgrade symfony/symfony to 8.0.12 or later

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