CVE-2026-47321
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk22th percentile - higher than 22% of all known CVEs
Summary
The CompressionFilter class in Apache MINA uses ZLib to deflate and inflate data, but does not control the resulting buffer size during decompression. Maliciously compressed data with a very high compression ratio can exhaust application memory. The fix introduces limits on the maximum decompressed size and compression ratio.
Risk Assessment
An attacker can send specially crafted data that expands to a huge size upon decompression, causing memory exhaustion and application unavailability (DoS). This affects any application using Apache MINA with CompressionFilter enabled.
Recommendation
Upgrade Apache MINA to a version containing the fix and configure CompressionFilter by passing the maxDecompressedSize parameter (and optionally maxDecompressRatio and decompressRatioMinSize) in the constructor or via the fluent API.
Other vulnerabilities in Apache MINA
See all- CVE-2026-94301Critical
The fix for CVE-2026-47065/ZDRES-232 ("resolveProxyClass Not Overridden - acceptMatchers Filter Bypass via java.lang.reflect.Proxy"), released on 2026-06-02 and announced as "Fully addressed" in MINA 2.2.8, 2.1.13 and 2.0.29, was committed to the 2.2.X branch only. The 2.0.X and 2.1.X maintenance branches never received the resolveProxyClass() override, so the 2.0.29 and 2.1.13 artifacts listed as fixed -- and every later release on those lines, up to and including the current 2.0.30 and 2.1.14 -- remain vulnerable to the exact allow-list bypass that CVE-2026-47065 was meant to close.
- CVE-2026-42779Critical
Apache MINA versions 2.1.0 to 2.1.11 and 2.2.0 to 2.2.6 are vulnerable to arbitrary code execution due to a lack of class verification in the AbstractIoBuffer.resolveClass() method. The fix was introduced in versions 2.1.12 and 2.2.7.
- CVE-2026-42778Critical
The fix for CVE-2026-41409 was not applied to the 2.1.X and 2.2.X branches of Apache MINA. The issue concerns an incomplete fix for CVE-2024-52046, where the classname allowlist for deserialization was applied too late.
- CVE-2023-35887Medium
CVE-2023-35887 vulnerability in Apache MINA exposes sensitive information to unauthorized actors. Logged users on SFTP servers may discover 'exists/does not exist' information about items outside the rooted tree using parent navigation or symlinks.
Original NVD description (English source)
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.