CVE-2026-54133 — mtdowling/jmespath.php
CRITICALCVE-2026-54133 is a critical-severity (CVSS 9.8) Improper Input Validation vulnerability in mtdowling/jmespath.php. A fix is available for mtdowling/jmespath.php — see the affected versions and patch details below.
jmespath.php has CompilerRuntime code injection via unescaped function names
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54133.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-54133 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 382,574 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
mtdowling/jmespath.phpReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Impact
mtdowling/jmespath.php can generate and execute attacker-controlled PHP code when JmesPath\CompilerRuntime is used with an attacker-controlled JMESPath expression. The compiler emits parsed JMESPath function names into generated PHP source without sufficient escaping. A crafted expression can cause the generated cache file to contain executable attacker-controlled PHP, which is then loaded by the compiler runtime.
A vulnerable flow is:
- An application accepts or constructs a JMESPath expression using attacker-controlled input.
- The expression is evaluated with
JmesPath\CompilerRuntime, or withJmesPath\search()whileJP_PHP_COMPILEis enabled. - The crafted expression uses a non-identifier value where the parser accepts a function callee.
- The compiler writes that value into generated PHP source without safely escaping it as a PHP string literal.
- The generated source is written to the compiled-expression cache directory.
CompilerRuntimeloads the generated cache file.- The injected PHP executes in the context of the affected application.
In that flow, an attacker can execute arbitrary PHP code with the privileges of the PHP process. The searched data document is not sufficient to exploit this issue by itself; the attacker must be able to influence the JMESPath expression string.
The default runtime used by JmesPath\search() is AstRuntime, which interprets the parsed expression tree and is not affected unless JP_PHP_COMPILE is enabled. Applications are most likely to be affected when they explicitly instantiate JmesPath\CompilerRuntime, enable JP_PHP_COMPILE as a performance optimization, and allow users to provide JMESPath expressions for filtering, querying, or transforming data.
Patches
The issue is patched in 2.9.1 and later.
Workarounds
If you cannot upgrade immediately, disable JP_PHP_COMPILE and do not use JmesPath\CompilerRuntime with attacker-controlled expressions. Use the default AstRuntime for untrusted expressions. Applications that must continue accepting untrusted JMESPath expressions before upgrading should ensure those expressions are never evaluated by the compiler runtime.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | mtdowling/jmespath.php | all versions | 2.9.1composer require mtdowling/jmespath.php:^2.9.1 |
Affected Products
jmespathjmespathDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mtdowling/jmespath.php, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mtdowling/jmespath.php to 2.9.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54133 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is CVE-2026-54133 in your dependencies?
Find it across Packagist, including transitive dependencies.