# CVE-2026-88355: Integer overflow in n/a

> Incorrect buffer size calculation in tinyexpr causes undefined behavior and deterministic process termination for arity-0 expression nodes.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 24 Sep 2026
- **Updated:** 6 Oct 2026
- **Also known as:** GHSA-8v6x-g49v-x5cf

## What is CVE-2026-88355?

CVE-2026-88355 is a high-severity vulnerability in n/a, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An incorrect buffer size calculation vulnerability exists in tinyexpr commit 4a7456e in new_expr(). For arity-0 expression nodes, including constants, variables, and zero-argument functions, the function allocates less memory than sizeof(te_expr) but treats the returned allocation as a complete te_expr object. This results in undefined behavior and can cause deterministic process termination in UBSan-instrumented builds.

Weakness: CWE-131 (Incorrect Calculation of Buffer Size)

## Which versions are affected by CVE-2026-88355?


## How do I fix CVE-2026-88355?

No fix has been published for CVE-2026-88355 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-88355 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88355 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-88355 and fix it if it is affected.

What it is: CVE-2026-88355 is a high-severity vulnerability in n/a, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-88355 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-2026-88355/ (Markdown: https://insights.sbomify.com/CVE-2026-88355/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-88355
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-88355
- OSV: https://osv.dev/vulnerability/CVE-2026-88355

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-88355/
Summaries are generated and may contain mistakes; the official description above is the record.