# CVE-2026-15396: IBM WebSphere Application Server IBM WebSphere Application Server - Liberty HTTP Request Smuggling

> Attackers can exploit HTTP request smuggling to poison caches, bypass firewalls, and conduct XSS attacks on IBM WebSphere Application Server.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 22 Oct 2026
- **Also known as:** GHSA-2fc8-vf8h-jfvw

## What is CVE-2026-15396?

CVE-2026-15396 is a medium-severity vulnerability in IBM WebSphere Application Server, published on 14 Sep 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 17.0.0.3 through 26.0.0.8 are vulnerable to HTTP request smuggling, caused by improper parsing of the HTTP transfer-encoding request header. By sending a specially crafted HTTP transfer-encoding request header, an attacker could exploit this vulnerability to poison the web cache, bypass web application firewall protection, and conduct XSS attacks.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2026-15396?


## How do I fix CVE-2026-15396?

No fix has been published for CVE-2026-15396 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15396 being exploited?

There is no known exploitation of CVE-2026-15396 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15396 and fix it if it is affected.

What it is: CVE-2026-15396 is a medium-severity vulnerability in IBM WebSphere Application Server, published on 14 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-2026-15396 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-2026-15396/ (Markdown: https://insights.sbomify.com/CVE-2026-15396/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15396
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15396
- OSV: https://osv.dev/vulnerability/CVE-2026-15396

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15396/
Summaries are generated and may contain mistakes; the official description above is the record.