AsyncHttpClient stores cookie for an unrelated domain (cookie tossing) via ThreadSafeCookieStore

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.0 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

EPSS

• CVE-2026-55688: 0.33% estimated exploitation activity in the next 30 days; percentile 26.22 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A cookie tossing / cookie injection issue (CWE-1275). 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 (RFC 6265 §5.3 step 6). 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. Who is Impacted Applications that use a single AsyncHttpClient instance - and thus the default, shared CookieStore - to reach both an attacker-influenced host and a trusted host. Typical exposure: crawlers, link-preview / webhook fetchers, SSRF-style "fetch this URL" features, multi-backend aggregators, or following redirects to an attacker-controlled host. The attacker can write a cookie the client presents to the victim host (session fixation, overwriting a session id / CSRF-token cookie); they cannot read the victim host's cookies. Applications that talk only to a fixed…

Published by the source

26 Aug 2026, 14:35 UTC

Last modified by the source

10 Sep 2026, 03:51 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-m452-q8c9-rg2f

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-m452-q8c9-rg2f

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# Patch Next advisory brief: CVE-2026-55688

Advisory: AsyncHttpClient stores cookie for an unrelated domain (cookie tossing) via ThreadSafeCookieStore
IDs: CVE-2026-55688, GHSA-m452-q8c9-rg2f
Record: https://patchnext.com/advisories/cve-2026-55688 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.asynchttpclient:async-http-client 3.0.11, 2.16.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.asynchttpclient:async-http-client: affected >= 3.0.0.Beta1, < 3.0.11; >= 2.0.0, < 2.16.0; fixed in 3.0.11, 2.16.0

## Suggested inspection (read-only)
- Maven org.asynchttpclient:async-http-client: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.asynchttpclient:async-http-client.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-m452-q8c9-rg2f (OSV record GHSA-m452-q8c9-rg2f lists affected ranges: Maven org.asynchttpclient:async-http-client >=3.0.0.Beta1 =2.0.0 <2.16.0 (fixed))
- Verified: https://github.com/advisories/GHSA-m452-q8c9-rg2f (GitHub-reviewed advisory GHSA-m452-q8c9-rg2f lists affected ranges: Maven org.asynchttpclient:async-http-client >=3.0.0.Beta1 =2.0.0 <2.16.0)

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