# CVE-2026-90473: msgpack-java through 0.9.12 Integer Overflow via MAP32

> Attackers can trigger an integer overflow in msgpack-java to desynchronize the parser and read attacker-controlled data, impacting applications using the library.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 12 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-90473, GHSA-9vjp-f3jg-99pq, UBUNTU-CVE-2026-90473

## What is CVE-2026-90473?

CVE-2026-90473 is a medium-severity vulnerability in msgpack-java, published on 12 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

msgpack-java through 0.9.12 contains an integer overflow vulnerability in MessageUnpacker.skipValue() when processing MAP32 containers with large element counts. Attackers can supply a MAP32 element count at or above 0x40000000 that wraps when doubled, causing the parser cursor to desynchronize and attacker-controlled data to be returned in place of later fields.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-90473?


## How do I fix CVE-2026-90473?

No fix has been published for CVE-2026-90473 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90473 being exploited?

There is no known exploitation of CVE-2026-90473 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90473 and fix it if it is affected.

What it is: CVE-2026-90473 is a medium-severity vulnerability in msgpack-java, published on 12 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90473 in the wild and no public exploit code.

Affected product: msgpack-java. 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-2026-90473/ (Markdown: https://insights.sbomify.com/CVE-2026-90473/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90473
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90473
- OSV: https://osv.dev/vulnerability/CVE-2026-90473

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90473/
Summaries are generated and may contain mistakes; the official description above is the record.