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.

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Mon, 21 Sep 2026 19:30:00 +0000

Type Values Removed Values Added
References

Mon, 21 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 21 Sep 2026 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Apache
Apache mina
Vendors & Products Apache
Apache mina

Mon, 21 Sep 2026 08:00:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache MINA: Unbounded Decompression Amplification DoS in Zlib.inflate
Weaknesses CWE-409
CWE-789
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-09-21T18:09:30.104Z

Reserved: 2026-05-19T07:41:55.668Z

Link: CVE-2026-47321

cve-icon Vulnrichment

Updated: 2026-09-21T18:09:30.104Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-21T08:16:37.520

Modified: 2026-09-21T19:17:06.247

Link: CVE-2026-47321

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-21T10:00:12Z

Weaknesses