Vulnerability · Published Sep 17, 2026 · Assigned by GitHub_M
CVE-2026-85721AsyncHttpClient: Unbounded HTTP/1.1 response decompression enables a decompression-bomb denial of service
High 7.5
In plain English
A high-severity uncontrolled resource consumption in async-http-client from AsyncHttpClient. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | async-http-client | no fix listed | DEBIAN-CVE-2026-85721 |
| Maven | org.asynchttpclient:async-http-client | 2.16.1 | GHSA-7grg-jcf7-rpmx |
| Maven | org.asynchttpclient:async-http-client | 3.0.12 | GHSA-7grg-jcf7-rpmx |
| Ubuntu:22.04:LTS | async-http-client | no fix listed | UBUNTU-CVE-2026-85721 |
| Ubuntu:24.04:LTS | async-http-client | no fix listed | UBUNTU-CVE-2026-85721 |
| Ubuntu:26.04:LTS | async-http-client | no fix listed | UBUNTU-CVE-2026-85721 |
| Ubuntu:26.10 | async-http-client | no fix listed | UBUNTU-CVE-2026-85721 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| AsyncHttpClient | async-http-client | >= 2.0.0, < 2.16.1>= 3.0.0, < 3.0.12 |
Weakness: CWE-400, CWE-409 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-7grg-jcf7-rpmx x_refsource_CONFIRM
- https://github.com/AsyncHttpClient/async-http-client/commit/5ee2841cbf268bba4a200578be3938ccfc6cc6d6 x_refsource_MISC
- https://github.com/AsyncHttpClient/async-http-client/commit/663a1a91757904b22cfe37e2e6049f1f8ea6ae59 x_refsource_MISC
- https://github.com/AsyncHttpClient/async-http-client/commit/e1871a19972fb496be1b8ac6be11d79e22ff2162 x_refsource_MISC
- https://github.com/AsyncHttpClient/async-http-client/commit/e9f2f7423e0f6503f529656f2955a1317e56ba14 x_refsource_MISC