# CVE-2026-78384: Apache CXF: Unbounded DEFLATE Decompression in CXF JOSE/JWE and SAML Processing (Decompression Bomb)

> Attackers can cause denial of service via decompression bombs in Apache CXF JWE and SAML processing by sending small payloads that expand to consume excessive memory.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** CLEANSTART-2026-EX41595, GHSA-m259-q69p-995q

## What is CVE-2026-78384?

CVE-2026-78384 is a high-severity denial of service vulnerability in Apache Cxf, published on 9 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

CompressionUtils.inflate() decompressed attacker-controlled DEFLATE data with no output-size cap. A small (~KB) crafted payload could expand to gigabytes on the heap. Reachable via JWE decryption when zip=DEF (e.g. JoseSessionTokenProvider with RSA-OAEP key wrap) and via SAML redirect/POST binding token inflation — in both cases decompression happens before/independent of trust validation.

Fix: Added a configurable maximum inflated-size cap (default 10 MiB, org.apache.cxf.compression-max-inflated-size system property) to CompressionUtils.inflate(); aborts with DataFormatException once exceeded.
Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Weakness: CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification))

## Which versions are affected by CVE-2026-78384?

It affects 1 product.


Products: Apache Cxf.

## How do I fix CVE-2026-78384?

Upgrade to a fixed version.

## Is CVE-2026-78384 being exploited?

There is no known exploitation of CVE-2026-78384 in the wild and no public exploit code.

## Other vulnerabilities in Apache Cxf

- [CVE-2012-2379](https://insights.sbomify.com/CVE-2012-2379/): XML Signature/Encryption Not Validated in Apache CXF (critical 10.0)
- [CVE-2026-66909](https://insights.sbomify.com/CVE-2026-66909/): Apache CXF: Unsafe deserialization of inbound JMS ObjectMessage (critical 9.8)
- [CVE-2026-68079](https://insights.sbomify.com/CVE-2026-68079/): Apache CXF: DefaultEncryptingCodeDataProvider allows unlimited authorization code replay (critical 9.8)
- [CVE-2026-50628](https://insights.sbomify.com/CVE-2026-50628/): Apache CXF: OAuth2: Inverted IP Binding Check Defeats Security Control (critical 9.8)
- [CVE-2025-48913](https://insights.sbomify.com/CVE-2025-48913/): Apache CXF: Untrusted JMS configuration can lead to RCE (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-78384 and fix it if it is affected.

What it is: CVE-2026-78384 is a high-severity denial of service vulnerability in Apache Cxf, published on 9 Oct 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-2026-78384 in the wild and no public exploit code.

Affected product: Apache Cxf. 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-2026-78384/ (Markdown: https://insights.sbomify.com/CVE-2026-78384/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-78384
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-78384
- OSV: https://osv.dev/vulnerability/CVE-2026-78384

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-78384/
Summaries are generated and may contain mistakes; the official description above is the record.