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

High 7.5 Published 9 Oct 2026 Updated 15 Oct 2026

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.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

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

Which versions are affected by CVE-2026-78384?

It affects 1 product.

Products include Apache Cxf.

How do I fix CVE-2026-78384?

Upgrade to a fixed version.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-78384 being exploited?

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

All Apache Cxf vulnerabilities

Sources

Also known as CLEANSTART-2026-EX41595, GHSA-m259-q69p-995q.