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Fencer Vulns
medium 4.0

CVE-2026-55688 json

AsyncHttpClient: Cookie stored for an unrelated domain (cookie tossing) via ThreadSafeCookieStore

published 2026-07-01 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-41134 , GHSA-m452-q8c9-rg2f

cvss
4.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 26%
public exploits
0
none known

Summary

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. In versions from 2.0.0 prior to 2.16.0 and from 3.0.0.Beta1 prior to 3.0.11, ThreadSafeCookieStore stored a cookie under the value of its Domain attribute without verifying that the responding host is allowed to set a cookie for that domain, leading to a cookie tossing / cookie injection issue. A host the client connects to can therefore plant a cookie scoped to an unrelated domain, and the client will then send that cookie on later requests to that domain. Applications that use a single AsyncHttpClient instance - and thus the default, shared CookieStore - to reach both an attacker-influenced host and a trusted host are impacted. This issue has been fixed in versions 2.16.0 and 3.0.11.

Patch / fix

  • maven org.asynchttpclient:async-http-client 2.16.0, 3.0.11
  • asynchttpclient_project async-http-client 2.16.0, 3.0.11
  • org.asynchttpclient async-http-client 2.16.0, 3.0.11
  • async-http-client Debian 12 2.12.3-1+deb12u1

debian advisories DEBIAN-CVE-2026-55688

  • async-http-client Ubuntu 22.04 LTS 2.12.3-1ubuntu0.22.04.1
  • async-http-client Ubuntu 24.04 LTS 2.12.3-1ubuntu0.24.04.1
  • async-http-client Ubuntu 26.04 LTS 2.12.3-1ubuntu1.1
  • async-http-client Ubuntu Pro 20.04 LTS 2.6.0-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2026-55688

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-55688 updated cvss 4.0

async-http-client: AsyncHttpClient: Cookie injection allows planting cookies for unrelated domains

  • Red Hat JBoss Enterprise Application Platform Expansion Pack async-http-client, async-http-client-netty-utils
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
GitHub 3.1 4.0 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven org.asynchttpclient:async-http-client
>=3.0.0.Beta1, <3.0.11
>=2.0.0, <2.16.0
3.0.11
2.16.0

Affected products

  • AsyncHttpClient async-http-client

Classification

Weakness
  • CWE-1275 Sensitive Cookie with Improper SameSite Attribute

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.