---
title: "CVE-2026-54133: jmespath.php has CompilerRuntime code injection via unescaped function names"
url: https://erroneo.us/security/cve/CVE-2026-54133/
description: "CVE-2026-54133 (mtdowling/jmespath.php (Composer (PHP))): jmespath.php allows users to use JMESPath, software for declaratively specifying how to extract…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-06-12
date_modified: 2026-08-18
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-54133"
kev: false
cvss: 9.8
epss: 0.00564
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-54133: jmespath.php has CompilerRuntime code injection via unescaped function names

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 46: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 46% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes mtdowling/jmespath.php (Composer (PHP)) < 2.9.1, fixed in 2.9.1 . Check your lockfile, including transitive dependencies.

## What it is

jmespath.php allows users to use JMESPath, software for declaratively specifying how to extract elements from a JSON document, in PHP applications with PHP data structures. Versions prior to 2.9.1 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. The issue is patched in 2.9.1 and later. As a workaround, disable JPPHPCOMPILE 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

- Composer (PHP) `mtdowling/jmespath.php` < 2.9.1 → fixed: 2.9.1

## Affected products (CVE record)

- jmespath jmespath.php: < 2.9.1

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.56% probability of exploitation activity in the next 30 days; percentile 46.

## Sources

- [GitHub Advisory GHSA-pcw8-m77r-2528](https://github.com/advisories/GHSA-pcw8-m77r-2528)
- [CVE.org record CVE-2026-54133](https://www.cve.org/CVERecord?id=CVE-2026-54133)
- [NVD entry CVE-2026-54133](https://nvd.nist.gov/vuln/detail/CVE-2026-54133)
- [github.com](https://github.com/jmespath/jmespath.php/security/advisories/GHSA-pcw8-m77r-2528)
- [github.com](https://github.com/FriendsOfPHP/security-advisories/blob/master/mtdowling/jmespath.php/CVE-2026-54133.yaml)

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Source page: https://erroneo.us/security/cve/CVE-2026-54133/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt