CyberSecBulletin
CVE-2026-78384NVD status: Analyzed

Apache CXF: Improper Handling of Highly Compressed Data (Data Amplification)

Published Updated By the CyberSecBulletin desk

CVE-2026-78384 is a high-severity improper handling of highly compressed data (data amplification) vulnerability in Apache CXF from Apache, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 4.2.4, 4.1.9, 3.6.13 as the first without the flaw, so updating Apache CXF to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.37% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Apache CXF to 4.2.4 or 4.1.9 or 3.6.13, whichever matches your release line, or a later version.
  2. Update Cxf to 3.6.13 or 4.1.9 or 4.2.4, whichever matches your release line, or a later version.
  3. Read the advisory on lists.apache.org for workarounds and exact fixed builds.
  4. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
ApacheApache CXF4.2.0 up to, but not including, 4.2.4; 4.0.0 up to, but not including, 4.1.9; before 3.6.134.2.4, 4.1.9, 3.6.13
ApacheCxfbefore 3.6.13; 4.0.0 up to, but not including, 4.1.9; 4.2.0 up to, but not including, 4.2.43.6.13, 4.1.9, 4.2.4

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by CISA (ADP).

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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Handling of Highly Compressed Data (Data Amplification)

The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.

More Improper Handling of Highly Compressed Data (Data Amplification) vulnerabilities (CWE-409)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Other vulnerabilities in Apache CXF

All Apache CXF vulnerabilities

Recent Improper Handling of Highly Compressed Data (Data Amplification) vulnerabilities

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