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CVE-2026-85721
Published:September 17, 2026
Updated:September 22, 2026
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.
Affected Packages
https://github.com/AsyncHttpClient/async-http-client.git (GITHUB):
Affected version(s) >=async-http-client-project-3.0.0 <async-http-client-project-3.0.12
Fix Suggestion:
Update to version async-http-client-project-3.0.12
https://github.com/AsyncHttpClient/async-http-client.git (GITHUB):
Affected version(s) >=async-http-client-project-2.14.5 <async-http-client-project-2.16.1
Fix Suggestion:
Update to version async-http-client-project-2.16.1
org.asynchttpclient:async-http-client (JAVA):
Affected version(s) >=2.0.0 <2.16.1
Fix Suggestion:
Update to version 2.16.1
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CVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Improper Handling of Highly Compressed Data (Data Amplification)
Uncontrolled Resource Consumption
EPSS
Base Score:
0.35