# CVE-2026-8400: Deserialization in WebSphere Application Server

> A flaw in the IBM Java SDK ORB component allows a malicious IIOP server to trigger arbitrary class instantiation, potentially leading to code execution.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Aug 2026
- **Updated:** 6 Aug 2026
- **Also known as:** GHSA-m4rx-9mrh-59g9

## What is CVE-2026-8400?

CVE-2026-8400 is a high-severity unsafe deserialization vulnerability in Ibm Websphere Application Server, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

IBM WebSphere Application Server 8.5, and 9.0 and IBM WebSphere Application Server - Liberty Continuous delivery has a flaw in the ORB component in IBM SDK, Java Technology Edition, may allow a malicious IIOP server to induce loading and instantation of arbitrary classes.

Weakness: CWE-470 (Use of Externally-Controlled Input to Select Classes or Code)

## Which versions are affected by CVE-2026-8400?

It affects 1 product.


Products: Ibm Websphere Application Server.

## How do I fix CVE-2026-8400?

Apply the vendor's patch.

## Is CVE-2026-8400 being exploited?

There is no known exploitation of CVE-2026-8400 in the wild and no public exploit code.

## Other vulnerabilities in Ibm Websphere Application Server

- [CVE-2015-1920](https://insights.sbomify.com/CVE-2015-1920/): Code injection in n/a (critical 10.0)
- [CVE-2013-0462](https://insights.sbomify.com/CVE-2013-0462/): Other in n/a (critical 10.0)
- [CVE-2011-1377](https://insights.sbomify.com/CVE-2011-1377/): Security feature bypass in n/a (critical 10.0)
- [CVE-2010-3186](https://insights.sbomify.com/CVE-2010-3186/): Other in n/a (critical 10.0)
- [CVE-2009-1899](https://insights.sbomify.com/CVE-2009-1899/): Information disclosure in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8400 and fix it if it is affected.

What it is: CVE-2026-8400 is a high-severity unsafe deserialization vulnerability in Ibm Websphere Application Server, published on 5 Aug 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-2026-8400 in the wild and no public exploit code.

Affected product: Ibm Websphere Application Server. 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-2026-8400/ (Markdown: https://insights.sbomify.com/CVE-2026-8400/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8400
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8400
- OSV: https://osv.dev/vulnerability/CVE-2026-8400

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-8400/
Summaries are generated and may contain mistakes; the official description above is the record.