Heym builds and runs agentic systems and business-process automations on self-hosted infrastructure. Prior to 0.0.40, an authenticated user who can create or edit a workflow with an Agent custom Python tool can bypass the blacklist-based sandbox in backend/app/services/python_tool_executor.py because allowed standard-library modules expose operating-system, process, and filesystem capabilities through public attributes that pass _safe_import() and _validate_code_safety(). The runner then executes the supplied tool with exec(), permitting commands and file operations as the backend application user; self-registration affects reachability, but portal triggering alone does not grant code control. This issue is fixed in 0.0.40.
CVE-2026-55376
HIGHPre-NVD 8.88.8ElevatedEG-KEV Tier 3: ElevatedEG-KEV is EchelonGraph's own tiering of exploitation signals from CISA KEV, CISA's SSVC data (Vulnrichment), ransomware data, public exploit-code references and EPSS.Tier 3 is not evidence of exploitation. It means public exploit code is referenced, or CISA's SSVC data says "public PoC", or EPSS ranks the CVE in the top 5%.Signals for this CVE: CISA's SSVC exploitation value: public PoC.EchelonGraph confidence 38%: a heuristic from the tier and the number of signals, not a measured probability.
EchelonGraph scoreMEDIUM confidence
“—” beside the score: it is equal to the CVSS score beside it.
This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (39th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Also known asEUVD-2026-98740 (ENISA EUVD)Source: ENISA EUVD
8.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
- CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 8.8Exploit: No code on recordExposed services: Not assessed
A fix is available — apply it.
- CVSS v3
- 8.8
- EG Score
- 8.8HIGHmedium confidence
- EG Risk
- 56EG Risk 56/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity88% × 45%Impact severity (EG Severity): CVSS 8.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation40% × 40%EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low, Track* at medium and Attend at high mission impact.Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.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
- 0.5%
- EPSS %ILE
- 39th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (8.8): severity, escalated by confirmed exploitation. This CVE's 8.8 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
- EG Likelihood
- 0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track* at medium mission impactTrack at low, Track* at medium and Attend at high mission impact.CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track 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). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
October 13, 2026
Last Modified
October 16, 2026
Advisory Details (3)
Auto-updated Oct 13, 2026Patch available. Sources: github_release, github, github_commit.
GitHub release Patch Available
v0.0.40
Patch available: heymrun/heym v0.0.40
https://github.com/heymrun/heym/releases/tag/v0.0.40GitHub commit Patch Available
commit b36d795c6ea8 (heymrun/heym)
Patch available: heymrun/heym v0.0.100 (contains commit b36d795c6ea8)
https://github.com/heymrun/heym/commit/b36d795c6ea841b8f1b511a0952e274487ee4ef3GitHub advisoryMentions a patch (unverified)
heym Python Tool Sandbox Escape · Advisory · heymrun/heym · GitHub
https://github.com/heymrun/heym/security/advisories/GHSA-wcgw-9hfw-f6f2Weakness Classification(3)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 28× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.
- 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-29 16:51 UTCEG score recompute
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 39th percentile
- 2026-10-25 14:19 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-23 07:39 UTCEG score recompute
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-18 03:30 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-16 22:26 UTCEG score recompute
- 2026-10-16 22:07 UTCEG score recompute
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.4% · 28th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.4% · 28th percentile
Show 3 moreShow fewer
- 2026-10-13 16:28 UTCEG score recompute
- 2026-10-13 15:21 UTCEG score recomputeFirst assessed: 8.8 HIGH
- 2026-10-13 15:19 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-55376?
CVE-2026-55376 is a high-severity vulnerability; its CVE record was published on October 13, 2026. Heym builds and runs agentic systems and business-process automations on self-hosted infrastructure. Prior to 0.0.40, an authenticated user who can create or edit a workflow with an Agent custom Python tool can bypass the blacklist-based sandbox in backend/app/services/python_tool_executor.py…
When was the CVE record for CVE-2026-55376 published?
The CVE record for CVE-2026-55376 was published on October 13, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 16, 2026; the record at its source may have been updated since.
Is CVE-2026-55376 actively exploited?
CVE-2026-55376 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (39th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55376?
CVE-2026-55376 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-2026-55376?
A fix for CVE-2026-55376 is available: update to the fixed version the vendor names in its advisory.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-55376
Is Your Infrastructure Affected by CVE-2026-55376?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.