---
id: CVE-2026-100864
title: >-
  heym before 0.0.91 contains a sandbox escape vulnerability in the expression
  engine's DotList map/filter and fallback resolver that allows authenticated
  users to execute arbitrary Python code
summary: >-
  heym before 0.0.91 contains a sandbox escape vulnerability in the expression
  engine's DotList map/filter and fallback resolver that allows authenticated
  users to execute arbitrary Python code. Attackers can craft workflow
  expressions usi…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-94
vendor: heymrun
product: heym
affected:
  - heym < 0.0.91
published: '2026-09-27'
updated: '2026-09-28'
sourceUpdated: '2026-09-28T20:57:50.143'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-100864'
references:
  - url: 'https://github.com/heymrun/heym/security/advisories/GHSA-87x2-9jwx-7gh4'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/heym-before-0.0.91-remote-code-execution-via-expression-engine
    label: disclosure@vulncheck.com
  - url: 'https://github.com/heymrun/heym/security/advisories/GHSA-87x2-9jwx-7gh4'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-28T16:02:30.424440Z'
ingestedAt: '2026-09-27T02:41:45.582Z'
epss: 0.00859
epssPercentile: 0.58287
---

## Overview

heym before 0.0.91 contains a sandbox escape vulnerability in the expression engine's DotList map/filter and fallback resolver that allows authenticated users to execute arbitrary Python code. Attackers can craft workflow expressions using dunder attribute access through item expressions or the fallback resolver to access os.system and execute commands as the backend process.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.