# CVE-2026-100842: MONAI through 1.6.0 _get_fake_spatial_shape eval() Sandbox Bypass via Attribute Chains

> Attacker can execute arbitrary code via eval injection in MONAI bundle verification if they control bundle metadata.

- **Severity:** High 7.3 (`CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Sep 2026
- **Updated:** 30 Sep 2026
- **Also known as:** GHSA-h89g-r5pc-wxfm, GHSA-j335-cfj5-2fw8, PYSEC-2026-4017

## What is CVE-2026-100842?

CVE-2026-100842 is a high-severity code injection vulnerability in Project-MONAI MONAI, published on 27 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

MONAI through 1.6.0 contains an eval injection vulnerability in _get_fake_spatial_shape() in monai/bundle/scripts.py. The function validates shape expressions with a helper that walks the AST and only collects ast.Name nodes, rejecting any name other than 'p' or 'n', before passing the string to eval(). Expressions built solely from constants and attribute, subscript, or call nodes (for example "(1).__class__.__bases__[0].__subclasses__()" or "int.__class__.__init__.__globals__") contain no ast.Name nodes and therefore bypass the allowlist. Because the shape value originates from bundle metadata consumed by _get_real_input_data and verify_net_in_out (reachable through the bundle 'verify_net_in_out' CLI flow), an attacker who can influence a bundle's metadata can escape the eval sandbox via object introspection chains and achieve code execution in this non-default flow.

Weakness: CWE-95 (Improper Neutralization of Directives in Dynamically Evaluated Code)

## Which versions are affected by CVE-2026-100842?

1 open source package ship an affected version, including monai. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `monai` | PyPI | All versions | 1.6.1rc0 |

Products: Project-Monai Monai.

## How do I fix CVE-2026-100842?

Upgrade monai to 1.6.1rc0 or later.

## Is CVE-2026-100842 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100842 exists.

## Other vulnerabilities in Project-MONAI MONAI

- [CVE-2026-100846](https://insights.sbomify.com/CVE-2026-100846/): MONAI before 1.5.2 Remote Code Execution via Pickle Deserialization (high 8.8)
- [CVE-2026-100844](https://insights.sbomify.com/CVE-2026-100844/): MONAI before 1.6.0 OS Command Injection via dataset_name_or_id (high 8.6)
- [CVE-2026-100840](https://insights.sbomify.com/CVE-2026-100840/): MONAI through 1.6.0 Remote Code Execution via bundle configuration (high 8.5)
- [CVE-2026-100841](https://insights.sbomify.com/CVE-2026-100841/): MONAI through 1.6.0 PersistentDataset Remote Code Execution via Pickle Cache (high 8.5)
- [CVE-2026-100843](https://insights.sbomify.com/CVE-2026-100843/): MONAI before 1.6.0 Remote Code Execution via algo_from_pickle (high 8.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-100842 and fix it if it is affected.

What it is: CVE-2026-100842 is a high-severity code injection vulnerability in Project-MONAI MONAI, published on 27 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-100842 exists.

Affected packages and fixed versions:
- monai (PyPI): affected all versions; fixed in 1.6.1rc0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-100842/ (Markdown: https://insights.sbomify.com/CVE-2026-100842/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-100842
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-100842
- OSV: https://osv.dev/vulnerability/CVE-2026-100842

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-100842/
Summaries are generated and may contain mistakes; the official description above is the record.