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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-85721
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-17 16:18:16 UTC
Updated2026-09-17 18:17:12 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

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

EPSS: 0.003500000 probability, percentile 0.287340000 (date 2026-09-19)

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA AsyncHttpClient Async-http-client affected >= 2.0.0, < 2.16.1 Not specified
CNA AsyncHttpClient Async-http-client affected >= 3.0.0, < 3.0.12 Not specified

References

ReferenceSourceLinkTags
github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-7g... [email protected] github.com
github.com/AsyncHttpClient/async-http-client/commit/e9f2f7423e0f6503f529... [email protected] github.com
github.com/AsyncHttpClient/async-http-client/commit/5ee2841cbf268bba4a20... [email protected] github.com
github.com/AsyncHttpClient/async-http-client/commit/663a1a91757904b22cfe... [email protected] github.com
github.com/AsyncHttpClient/async-http-client/commit/e1871a19972fb496be1b... [email protected] github.com
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