CVE-2026-100864

HIGHPre-NVD 8.88.8—
EchelonGraph scoreHIGH confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2026-09-27. A secondary CVSS source baseline 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this weekElevated
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 8.8Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
8.8
EG Score
8.8HIGHhigh confidence
EG Risk
56
EG Risk 56/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.7%
EPSS %ILE
50th
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 27, 2026

Last Modified

September 28, 2026

Advisory Details (2)

Auto-updated Sep 27, 2026
Patch available. Sources: github.
generic

heym before 0.0.91 Remote Code Execution via Expression Engine | Advisories | VulnCheck

https://www.vulncheck.com/advisories/heym-before-0.0.91-remote-code-execution-via-expression-engine
github Patch Available

Expression engine sandbox escape via DotList map/filter and fallback resolver leads to authenticated RCE · Advisory · heymrun/heym · GitHub

https://github.com/heymrun/heym/security/advisories/GHSA-87x2-9jwx-7gh4

Vendor Advisories for CVE-2026-100864(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 31× in last 7d / 34× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-04 03:59 UTCGHSA enrichment
  2. 2026-10-03 16:29 UTCEG score recompute
  3. 2026-10-03 16:28 UTCGHSA enrichment
  4. 2026-10-03 14:25 UTCEPSS rescore
  5. 2026-10-03 04:58 UTCGHSA enrichment
  6. 2026-10-02 17:27 UTCEG score recompute
  7. 2026-10-02 17:27 UTCGHSA enrichment
  8. 2026-10-02 05:53 UTCEG score recompute
  9. 2026-10-02 05:53 UTCGHSA enrichment
  10. 2026-10-01 19:49 UTCEPSS rescore
  11. 2026-10-01 18:23 UTCGHSA enrichment
  12. 2026-10-01 06:49 UTCGHSA enrichment
  13. 2026-09-30 19:17 UTCEG score recompute
  14. 2026-09-30 19:17 UTCGHSA enrichment
  15. 2026-09-30 15:02 UTCEPSS rescore
  16. 2026-09-30 07:47 UTCGHSA enrichment
  17. 2026-09-29 20:16 UTCEG score recompute
  18. 2026-09-29 20:16 UTCGHSA enrichment
  19. 2026-09-29 15:20 UTCEPSS rescore
  20. 2026-09-29 08:43 UTCEG score recompute
  21. 2026-09-29 08:43 UTCGHSA enrichment
  22. 2026-09-28 21:13 UTCGHSA enrichment
  23. 2026-09-28 17:38 UTCEG score recompute
  24. 2026-09-28 17:37 UTCGHSA enrichment
  25. 2026-09-28 16:34 UTCEG score recompute
Show 9 more
  1. 2026-09-28 16:34 UTCGHSA enrichment
  2. 2026-09-28 13:50 UTCEPSS rescore
  3. 2026-09-28 13:12 UTCGHSA enrichment
  4. 2026-09-28 01:41 UTCGHSA enrichment
  5. 2026-09-27 14:06 UTCEG score recompute
  6. 2026-09-27 14:06 UTCGHSA enrichment
  7. 2026-09-27 02:36 UTCEG score recompute
  8. 2026-09-27 01:52 UTCEG score recompute
  9. 2026-09-27 01:49 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-100864?
CVE-2026-100864 is a high vulnerability published on September 27, 2026. 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…
When was CVE-2026-100864 disclosed?
CVE-2026-100864 was first published on September 27, 2026, with the most recent update on September 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100864 actively exploited?
CVE-2026-100864 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (50th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-100864?
CVE-2026-100864 has a CVSS base score of 8.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-100864?
A fix for CVE-2026-100864 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-100864 are linked in the Vendor Advisories panel on this page.

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