CVE-2026-47321 (GCVE-0-2026-47321)
Vulnerability from cvelistv5 – Published: 2026-09-21 07:43 – Updated: 2026-09-21 18:09
VLAI
EPSS
VEX
Title
Apache MINA: Unbounded Decompression Amplification DoS in Zlib.inflate
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.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-21 14:00 UTC
CWE
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://lists.apache.org/thread/y7xj1bl8qo47p9bkt… | mailing-listvendor-advisory |
| http://www.openwall.com/lists/oss-security/2026/09/21/1 |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Apache Software Foundation | Apache MINA |
Affected:
2.2.0 , < 2.2.8
(maven)
Affected: 2.1.0 , < 2.1.13 (maven) Affected: 2.0.0 , < 2.0.29 (maven) |
guessed |
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"value": "\u003cdiv\u003eThe 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.\u003c/div\u003e\u003cdiv\u003eSome compressed data may have a compression ration greater than 1 thousand, leading to an exhaustion of the application memory, as we don\u0027t control the deflated size.\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003eThe 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)\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003eFor application using this feature, it is highly recommended to create the\u0026nbsp;CompressionFilter and to pass the maximum limit as a forth constructor parameter, maxDecompressedSize:\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cblockquote\u003epublic \u003cspan\u003eCompressionFilter\u003c/span\u003e(final boolean compressInbound, final boolean compressOutbound, final int compressionLevel, final int maxDecompressedSize)\u003c/blockquote\u003e\u003cdiv\u003eOptionally one can also provide a\u0026nbsp;\u003cspan\u003e\u003cspan\u003e\u003cspan\u003emaxDecompressRatio\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u0026nbsp;fifth parameter, and a \u003cspan\u003e\u003cspan\u003e\u003cspan\u003edecompressRatioMinSize\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u0026nbsp;sixth parameter to allow small inflated files with a high compression ratio to still be accepted.\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003eHere are the additional constructor:\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cdiv\u003e\u003cblockquote\u003e\u003cp\u003epublic CompressionFilter(final boolean compressInbound, final boolean compressOutbound,\u003c/p\u003e\u003cp\u003e final int compressionLevel, final int maxDecompressedSize,\u003c/p\u003e\u003cp\u003e final long maxDecompressRatio, final long \u003cspan\u003edecompressRatioMinSize\u003c/span\u003e)\u003c/p\u003e\u003c/blockquote\u003e\u003c/div\u003e\u003c/div\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003eAlso note that a fluent API has been added to spare the users the pain to call a constructor with that many parameters:\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003e\u003c/div\u003e\u003cblockquote\u003e\u003cdiv\u003e\u2003CompressionFilter compressionFilter = new CompressionFilter()\u003c/div\u003e\u003cdiv\u003e\u2003\u2003\u2003 .setCompressionLevel(Zlib.\u003cspan\u003e\u003cspan\u003e\u003cspan\u003eCOMPRESSION_MAX\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e)\u003c/div\u003e\u003cdiv\u003e\u0026nbsp; .\u003cspan\u003e\u003cspan\u003esetMaxDecompressedSize\u003c/span\u003e\u003c/span\u003e(1_000_000)\u003c/div\u003e\u003cdiv\u003e\u0026nbsp; .\u003cspan\u003e\u003cspan\u003esetMaxDecompressRatio\u003c/span\u003e\u003c/span\u003e(100).\u003c/div\u003e\u003cdiv\u003e\u0026nbsp; .\u003cspan\u003e\u003cspan\u003esetDecompressRatioMinSize\u003c/span\u003e\u003c/span\u003e(100_000);\u0026nbsp;\u003c/div\u003e\u003cdiv\u003e\u003c/div\u003e\u003c/blockquote\u003e\u003cdiv\u003e\u003c/div\u003e\u003cdiv\u003e\u003cbr\u003e\u003c/div\u003e\u003cdiv\u003e\nApplications using Apache MINA are advised to upgrade and configure their CompressionFilter instance.\u003c/div\u003e"
}
],
"value": "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.\n\nSome compressed data may have a compression ration greater than 1 thousand, leading to an exhaustion of the application memory, as we don\u0027t control the deflated size.\n\n\n\n\nThe 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)\n\n\n\n\nFor application using this feature, it is highly recommended to create the\u00a0CompressionFilter and to pass the maximum limit as a forth constructor parameter, maxDecompressedSize:\n\n\n\n\npublic CompressionFilter(final boolean compressInbound, final boolean compressOutbound, final int compressionLevel, final int maxDecompressedSize)Optionally one can also provide a\u00a0maxDecompressRatio\u00a0fifth parameter, and a decompressRatioMinSize\u00a0sixth parameter to allow small inflated files with a high compression ratio to still be accepted.\n\n\n\n\nHere are the additional constructor:\n\n\n\n\n\n\npublic CompressionFilter(final boolean compressInbound, final boolean compressOutbound,\n\n\n\n final int compressionLevel, final int maxDecompressedSize,\n\n\n\n final long maxDecompressRatio, final long decompressRatioMinSize)\n\n\n\n\n\n\n\n\nAlso note that a fluent API has been added to spare the users the pain to call a constructor with that many parameters:\n\n\n\n\n\n\n\u2003CompressionFilter compressionFilter = new CompressionFilter()\n\n\u2003\u2003\u2003 .setCompressionLevel(Zlib.COMPRESSION_MAX)\n\n\u00a0 .setMaxDecompressedSize(1_000_000)\n\n\u00a0 .setMaxDecompressRatio(100).\n\n\u00a0 .setDecompressRatioMinSize(100_000);\u00a0\n\n\n\n\n\n\n\n\n\nApplications using Apache MINA are advised to upgrade and configure their CompressionFilter instance."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-409",
"description": "CWE-409: Improper Handling of Highly Compressed Data \u2014 Data Amplification",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-789",
"description": "CWE-789: Memory Allocation with Excessive Size Value",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-21T07:43:24.769Z",
"orgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"shortName": "apache"
},
"references": [
{
"tags": [
"mailing-list",
"vendor-advisory"
],
"url": "https://lists.apache.org/thread/y7xj1bl8qo47p9bktb11hg5v6k1d4dyj"
}
],
"source": {
"discovery": "UNKNOWN"
},
"title": "Apache MINA: Unbounded Decompression Amplification DoS in Zlib.inflate",
"x_generator": {
"engine": "Vulnogram 0.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "f0158376-9dc2-43b6-827c-5f631a4d8d09",
"assignerShortName": "apache",
"cveId": "CVE-2026-47321",
"datePublished": "2026-09-21T07:43:24.769Z",
"dateReserved": "2026-05-19T07:41:55.668Z",
"dateUpdated": "2026-09-21T18:09:30.104Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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