# CVE-2026-93475: Out-of-bounds Write via an Unbounded RSA Modulus in NetX Secure X.509


- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 20 Oct 2026
- **Updated:** 20 Oct 2026
- **Also known as:** GHSA-rcv5-vfff-25gh

## What is CVE-2026-93475?

CVE-2026-93475 is a critical vulnerability in Eclipse ThreadX - NetX Duo, published on 20 Oct 2026. 

### Official description

The X.509 parser in NetX Secure accepts an RSA public key of any size, but every signature-verification path decrypts into fixed-size buffers dimensioned for the `NX_CRYPTO_MAX_RSA_MODULUS_SIZE` default of 4096 bits. A certificate carrying a larger modulus drives an out-of-bounds write past a file-scope static during ordinary certificate-chain verification.

It is reachable pre-authentication. The issuer used for the crypto operation is looked up in the remote, peer-supplied store before the trusted store, so the attacker supplies the oversized key themselves as an intermediate in the chain they present. It triggers on a TLS or DTLS client verifying a malicious server's chain, and on a server performing client-certificate authentication.

Weakness: CWE-787 (Out-of-bounds Write), CWE-1284 (Improper Validation of Specified Quantity in Input)

## Which versions are affected by CVE-2026-93475?


## How do I fix CVE-2026-93475?

No fix has been published for CVE-2026-93475 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-93475 being exploited?

There is no known exploitation of CVE-2026-93475 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-93475 and fix it if it is affected.

What it is: CVE-2026-93475 is a critical vulnerability in Eclipse ThreadX - NetX Duo, published on 20 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-93475 in the wild and no public exploit code.

Affected product: Eclipse ThreadX - NetX Duo. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-93475/ (Markdown: https://insights.sbomify.com/CVE-2026-93475/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-93475
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-93475
- OSV: https://osv.dev/vulnerability/CVE-2026-93475

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-93475/
Summaries are generated and may contain mistakes; the official description above is the record.