OCTOBER 10, 2026
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Case File

CVE-2026-47321

HIGH · CVSS 7.5 EPSS 0.49%

Source: NVD + CISA KEV + EPSS · Published 2026-09-21 · Last synced 2026-10-10

CyberRota Analysis

AI-Generated

The CompressionFilter class in Apache is vulnerable due to inadequate control over the size of inflated data, potentially leading to application memory exhaustion when processing highly compressed inputs. This flaw can be exploited to cause denial-of-service conditions, making it critical for developers using this feature to implement the recommended size limits and ratios in their CompressionFilter configuration. Organizations utilizing Apache MINA should prioritize upgrading and properly configuring their instances to mitigate this risk.

CVE
CVE-2026-47321
Severity
HIGH
CVSS
7.5
EPSS
0.49%
Apache

Original NVD 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.