Bug 2536136 (CVE-2026-85721)

Summary: CVE-2026-85721 org.asynchttpclient/async-http-client: AsyncHttpClient: Denial of Service via unbounded HTTP response decompression
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: gmalinko, janstey, pdelbell, rstepani
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in AsyncHttpClient's automatic HTTP response decompression. With automatic decompression enabled (the default), the HTTP/1.1 path does not limit the total decompressed response size. A hostile or compromised server, or an attacker able to change a response in transit, can send a small compressed response that expands until the client's heap is exhausted, causing an `OutOfMemoryError` and denial of service. gzip, deflate, and snappy are always available as vectors; brotli and zstd apply when their optional codecs are present. AsyncHttpClient versions 2.0.0 through 2.16.0 and 3.0.0 through 3.0.11 are affected; versions 2.16.1 and 3.0.12 fix the issue. The HTTP/2 decompressor is also unbounded in versions 3.0.8 through 3.0.10.
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Description OSIDB Bzimport 2026-09-17 16:08:55 UTC 
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.