# CVE-2026-88390: Memory corruption in n/a

> Crafted JavaScript input triggers an out-of-bounds write in Espruino, causing memory corruption and potential denial of service in specific build configurations.

- **Severity:** High 7.7 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** GHSA-5c5x-qcqw-7rfq

## What is CVE-2026-88390?

CVE-2026-88390 is a high-severity memory corruption vulnerability in n/a, published on 24 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An out-of-bounds write vulnerability in jslGetTokenValueAsString() in Espruino 2v29 (commit bffc6d0) allows crafted JavaScript input containing an overlong token to trigger a one-byte write beyond the JsLex.token buffer in RELEASE/NO_ASSERT builds. The out-of-bounds write corrupts the adjacent tokenValue pointer, resulting in memory corruption and potentially causing application crashes or denial of service.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-88390?


## How do I fix CVE-2026-88390?

No fix has been published for CVE-2026-88390 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-88390 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88390 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-88390 and fix it if it is affected.

What it is: CVE-2026-88390 is a high-severity memory corruption vulnerability in n/a, published on 24 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-2026-88390 exists.

Affected product: n/a. 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-2026-88390/ (Markdown: https://insights.sbomify.com/CVE-2026-88390/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-88390
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-88390
- OSV: https://osv.dev/vulnerability/CVE-2026-88390

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-88390/
Summaries are generated and may contain mistakes; the official description above is the record.