---
title: "CVE-2026-100864: heym - Remote Code Execution"
description: "heym < 0.0.91 contains a sandbox escape vulnerability caused by dunder attribute access in the expression engine's DotList map/filter and fallback resolver, letting authenticated users execute arbitrary Python code."
url: https://panop.io/threat-heartbeat/CVE-2026-100864/
---

# CVE-2026-100864 heym - Remote Code Execution

heym < 0.0.91 contains a sandbox escape vulnerability caused by dunder attribute access in the expression engine's DotList map/filter and fallback resolver, letting authenticated users execute arbitrary Python code.

CVSS base score 8.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.69% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-100864)

## Details

Type

Remote Code Execution

Impact

Remote Code Execution

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Published

27 September 2026

Updated

15 October 2026

Weakness

[CWE-94](https://cwe.mitre.org/data/definitions/94.html)

## Vendor fix

Update to version 0.0.91 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-100864](https://nvd.nist.gov/vuln/detail/CVE-2026-100864)
- [https://github.com/heymrun/heym/security/advisories/GHSA-87x2-9jwx-7gh4](https://github.com/heymrun/heym/security/advisories/GHSA-87x2-9jwx-7gh4)
- [https://www.vulncheck.com/advisories/heym-before-0.0.91-remote-code-execution-via-expression-engine](https://www.vulncheck.com/advisories/heym-before-0.0.91-remote-code-execution-via-expression-engine)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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