Vulnerability details

CVE-2026-85721

AsyncHttpClient async-http-client

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

CVSS 3.1
7.5High

Official description

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.

CVSS scores

ScoreVersionSourceVector
7.5High 3.1 CVEProject cvelistV5 (CNA) (GitHub_M) CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

VendorProductVersionsSource
AsyncHttpClient async-http-client >= 2.0.0, < 2.16.1 CVEProject cvelistV5 (CNA)
AsyncHttpClient async-http-client >= 3.0.0, < 3.0.12 CVEProject cvelistV5 (CNA)

References and advisories

5
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Details

Published
2026-09-17
Last updated
2026-09-17
State
Published
Assigner (CNA)
GitHub_M

Exploit prediction (EPSS)

0.63%
Probability of exploitation in 30 days
50.3%
Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable
Yes
Exploitation
None
Technical impact
Partial

Weaknesses (CWE)

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