Vulnerability-Lookup

CVE-2026-85721 (GCVE-0-2026-85721)

Vulnerability from cvelistv5 – Published: 2026-09-17 15:55 – Updated: 2026-09-17 17:22

Title

AsyncHttpClient: Unbounded HTTP/1.1 response decompression enables a decompression-bomb denial of service

Summary

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. From 2.0.0 until 2.16.1 and 3.0.12, automatic response decompression on the HTTP/1.1 path uses ChannelManager.newHttpContentDecompressor() to install Http1ContentDecompressor without a cumulative output-size limit. A hostile or compromised server, or an attacker who can alter a response in transit, can send a small gzip, deflate, or snappy response that expands across chunks until the client exhausts its heap and raises OutOfMemoryError; brotli and zstd are also affected when their optional codecs are present. In versions 3.0.8 through 3.0.10, the HTTP/2 decompressor is also unbounded, so switching protocols does not mitigate the issue on those releases. A limit applied to each decode call is insufficient because the response can be delivered as many small chunks, so the fixed implementation tracks total decompressed bytes for the whole response. This issue is fixed in versions 2.16.1 and 3.0.12.

Severity

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-17 17:22 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption
CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)

Assigner

GitHub_M mitre root

References

5 references

URL	Tags
https://github.com/AsyncHttpClient/async-http-cli…	x_refsource_CONFIRM
https://github.com/AsyncHttpClient/async-http-cli…	x_refsource_MISC
https://github.com/AsyncHttpClient/async-http-cli…	x_refsource_MISC
https://github.com/AsyncHttpClient/async-http-cli…	x_refsource_MISC
https://github.com/AsyncHttpClient/async-http-cli…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
AsyncHttpClient	async-http-client	Affected: >= 2.0.0, < 2.16.1 Affected: >= 3.0.0, < 3.0.12	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-85721

Vulnerability from fkie_nvd - Published: 2026-09-17 16:18 - Updated: 2026-09-17 18:17

Severity

7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/AsyncHttpClient/async-http-client/commit/5ee2841cbf268bba4a200578be3938ccfc6cc6d6
	security-advisories@github.com	https://github.com/AsyncHttpClient/async-http-client/commit/663a1a91757904b22cfe37e2e6049f1f8ea6ae59
	security-advisories@github.com	https://github.com/AsyncHttpClient/async-http-client/commit/e1871a19972fb496be1b8ac6be11d79e22ff2162
	security-advisories@github.com	https://github.com/AsyncHttpClient/async-http-client/commit/e9f2f7423e0f6503f529656f2955a1317e56ba14
	security-advisories@github.com	https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-7grg-jcf7-rpmx

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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      "source": "security-advisories@github.com",
      "url": "https://github.com/AsyncHttpClient/async-http-client/commit/663a1a91757904b22cfe37e2e6049f1f8ea6ae59"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/AsyncHttpClient/async-http-client/commit/e1871a19972fb496be1b8ac6be11d79e22ff2162"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/AsyncHttpClient/async-http-client/commit/e9f2f7423e0f6503f529656f2955a1317e56ba14"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-7grg-jcf7-rpmx"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        },
        {
          "lang": "en",
          "value": "CWE-409"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-7GRG-JCF7-RPMX

Vulnerability from github – Published: 2026-09-17 17:18 – Updated: 2026-09-17 17:18

Summary

AsyncHttpClient's unbounded HTTP/1.1 response decompression enables a decompression-bomb denial of service

Details

Impact

With automatic response decompression enabled (the default), the HTTP/1.1 path decompresses response bodies with no limit on the total output size. A hostile or compromised server, or an attacker who can change a response in transit, can send a small compressed body that inflates without bound in memory, exhausting the client's heap and causing an OutOfMemoryError. gzip, deflate and snappy are always available as vectors; brotli and zstd apply only when those optional codecs are on the classpath.

Affected versions

3.x: up to and including 3.0.11
2.x: up to and including 2.16.0

The HTTP/2 path carries its own limit from 3.0.11 onward. On 3.0.8, 3.0.9 and 3.0.10 the HTTP/2 decompressor is also unbounded, so on those versions switching to HTTP/2 is not a mitigation.

Patches

Fixed in 3.0.12 on the 3.x line and in 2.16.1 on the 2.x line. The fix counts the decompressed bytes produced for each response and fails the response once the configured maximum is exceeded, so the limit applies to the whole body rather than to any single chunk.

Workarounds

On 3.x, disable automatic decompression (setEnableAutomaticDecompression(false)) and decompress manually with your own size limit. The 2.x line has no such setting; the decompressor is installed unconditionally, so the only option there is to remove the inflater handler through httpAdditionalChannelInitializer. On either line, running the client behind a proxy that caps response sizes also works.

Details

ChannelManager.newHttpContentDecompressor() created Netty's HttpContentDecompressor without any bound, and Netty's own maxAllocation parameter limits a single decode step rather than the accumulated size of a response, so it cannot bound a decompression bomb delivered as many small chunks. The fix tracks the accumulated decompressed size per response instead.

Note that 3.0.12 is itself affected by a separate issue, GHSA-rqf5-2wxv-rjf4, where a Digest challenge the client cannot read downgrades to Basic and sends the password in cleartext. Upgrade to 3.0.13 to pick up both fixes.

Severity

7.5 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Show details on source website

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.0.11"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.asynchttpclient:async-http-client"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.0.12"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.16.0"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "org.asynchttpclient:async-http-client"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.0.0"
            },
            {
              "fixed": "2.16.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-85721"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-409"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-17T17:18:56Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\nWith automatic response decompression enabled (the default), the HTTP/1.1 path decompresses response bodies with no limit on the total output size. A hostile or compromised server, or an attacker who can change a response in transit, can send a small compressed body that inflates without bound in memory, exhausting the client\u0027s heap and causing an OutOfMemoryError. gzip, deflate and snappy are always available as vectors; brotli and zstd apply only when those optional codecs are on the classpath.\n\n### Affected versions\n* 3.x: up to and including 3.0.11\n* 2.x: up to and including 2.16.0\n\nThe HTTP/2 path carries its own limit from 3.0.11 onward. On 3.0.8, 3.0.9 and 3.0.10 the HTTP/2 decompressor is also unbounded, so on those versions switching to HTTP/2 is not a mitigation.\n\n### Patches\nFixed in 3.0.12 on the 3.x line and in 2.16.1 on the 2.x line. The fix counts the decompressed bytes produced for each response and fails the response once the configured maximum is exceeded, so the limit applies to the whole body rather than to any single chunk.\n\n### Workarounds\nOn 3.x, disable automatic decompression (setEnableAutomaticDecompression(false)) and decompress manually with your own size limit. The 2.x line has no such setting; the decompressor is installed unconditionally, so the only option there is to remove the inflater handler through httpAdditionalChannelInitializer. On either line, running the client behind a proxy that caps response sizes also works.\n\n### Details\nChannelManager.newHttpContentDecompressor() created Netty\u0027s HttpContentDecompressor without any bound, and Netty\u0027s own maxAllocation parameter limits a single decode step rather than the accumulated size of a response, so it cannot bound a decompression bomb delivered as many small chunks. The fix tracks the accumulated decompressed size per response instead.\n\nNote that 3.0.12 is itself affected by a separate issue, GHSA-rqf5-2wxv-rjf4, where a Digest challenge the client cannot read downgrades to Basic and sends the password in cleartext. Upgrade to 3.0.13 to pick up both fixes.",
  "id": "GHSA-7grg-jcf7-rpmx",
  "modified": "2026-09-17T17:18:56Z",
  "published": "2026-09-17T17:18:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-7grg-jcf7-rpmx"
    },
    {
      "type": "WEB",
      "url": "https://github.com/AsyncHttpClient/async-http-client/commit/5ee2841cbf268bba4a200578be3938ccfc6cc6d6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/AsyncHttpClient/async-http-client/commit/663a1a91757904b22cfe37e2e6049f1f8ea6ae59"
    },
    {
      "type": "WEB",
      "url": "https://github.com/AsyncHttpClient/async-http-client/commit/e1871a19972fb496be1b8ac6be11d79e22ff2162"
    },
    {
      "type": "WEB",
      "url": "https://github.com/AsyncHttpClient/async-http-client/commit/e9f2f7423e0f6503f529656f2955a1317e56ba14"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/AsyncHttpClient/async-http-client"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "AsyncHttpClient\u0027s unbounded HTTP/1.1 response decompression enables a decompression-bomb denial of service"
}

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.

Detection rules are retrieved from Rulezet.

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.

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Action not permitted

CVE-2026-85721 (GCVE-0-2026-85721)

FKIE_CVE-2026-85721

GHSA-7GRG-JCF7-RPMX

Impact

Affected versions

Patches

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Details

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