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Fencer Vulns
high 7.5

CVE-2026-47321 json

Apache MINA: Unbounded Decompression Amplification DoS in Zlib.inflate

published 2026-09-21 48 d ago modified 2026-09-21 48 d ago also EUVD-2026-83858

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

The CompressionFilter class uses ZLib to deflate and inflate data sent and received. When we inflate incoming data, the filter does not control the resulting size, and create a buffer no matter what.

Some compressed data may have a compression ration greater than 1 thousand, leading to an exhaustion of the application memory, as we don't control the deflated size.

The fix adds such a control by allowing the application developer to provide a fixed size limit, which when reached throws an exception. It also allows the user to provide a compression ratio that should not be exceeded, protected the application from small inflated files that inflate in gigantic files, but with a grace limit for the resulting size (1Mb) to avoid false positive (like a very small file inflating with a high ratio, but resulting with a acceptable size, like a few thousands bytes)

For application using this feature, it is highly recommended to create the CompressionFilter and to pass the maximum limit as a forth constructor parameter, maxDecompressedSize:

public CompressionFilter(final boolean compressInbound, final boolean compressOutbound, final int compressionLevel, final int maxDecompressedSize)Optionally one can also provide a maxDecompressRatio fifth parameter, and a decompressRatioMinSize sixth parameter to allow small inflated files with a high compression ratio to still be accepted.

Here are the additional constructor:

public CompressionFilter(final boolean compressInbound, final boolean compressOutbound,

final int compressionLevel, final int maxDecompressedSize,

final long maxDecompressRatio, final long decompressRatioMinSize)

Also note that a fluent API has been added to spare the users the pain to call a constructor with that many parameters:

CompressionFilter compressionFilter = new CompressionFilter()

.setCompressionLevel(Zlib.COMPRESSION_MAX)

.setMaxDecompressedSize(1_000_000)

.setMaxDecompressRatio(100).

.setDecompressRatioMinSize(100_000);

Applications using Apache MINA are advised to upgrade and configure their CompressionFilter instance.

Patch / fix

  • Apache Software Foundation Apache MINA 2.0.29, 2.1.13, 2.2.8
  • mina2 Debian 14 2.2.9-1

debian advisories DEBIAN-CVE-2026-47321

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-47321 updated cvss 7.5

org.apache.mina/mina-core: Apache MINA: Denial of Service via unbounded decompression amplification

  • Red Hat OpenShift Developer Tools and Services ocp-tools-4/jenkins-rhel8, ocp-tools-4/jenkins-rhel9, jenkins 2.516.3.1758206866-3.el9, jenkins-2-plugins 4.19.1758207171-1.el9 Red Hat Enterprise Linux 9 maven-wagon, maven-wagon-javadoc, maven-wagon 3.5.3-9.el10 Red Hat Enterprise Linux 10 maven-wagon 3.5.3-9.el10
    affected: no fix available
  • Red Hat Fuse 7 mina-core 2.0.16
    affected: no fix planned “Will not fix”
  • Red Hat Enterprise Linux 8 maven-wagon, maven-wagon-ftp, maven-wagon-file, maven-wagon-http, maven-wagon-javadoc, maven-wagon-providers, +3 more Red Hat Enterprise Linux 9 maven-wagon, maven-wagon-javadoc
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
48 d ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Apache Software Foundation Apache MINA

Classification

Weakness
  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
  • CWE-789 Memory Allocation with Excessive Size Value

References

Sources

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