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No exploitation reportedFix available

CVE-2026-55688

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

No exploitation reported by the sources we read.

  • Published2026-07-01
  • Fixed in3.0.11 · 2.16.0
  • WeaknessCWE-1275

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-07-0120:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-55688?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-55688?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

OSV
async-http-client
BranchAffectedFixed in
3.0≥ 3.0.0.Beta1, < 3.0.113.0.11
2.x≥ 2.0.0, < 2.16.02.16.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-55688 Red Hat Product Security2 known affected

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

    async-http-client as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack · async-http-client-netty-utils as a component of Red Hat JBoss Enterprise Application Platform Expansion Pack

Full record on NVD

Fix

  1. Update async-http-client to 3.0.11 · 2.16.0
  2. Workaround from the vendor Red Hat Product Security CVE-2026-55688 · 2 productsMitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
  3. No fix available, says the vendor Red Hat Product Security CVE-2026-55688 · 2 productsFix deferred

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionnone2026-07-02
  • OpenCVESSVC decisionnone—
  • CNACVSS 3.14read 2026-10-23
  • CNAweakness (CWE)CWE-1275read 2026-10-23
  • FIRST EPSSEPSS score0.3 %2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N
Published
2026-07-01
Last Modified
2026-08-06
NVD status
Awaiting Analysis

Frequently asked questions

What is CVE-2026-55688?

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.

Is CVE-2026-55688 actively exploited?

Active exploitation of CVE-2026-55688 has not been confirmed. Its EPSS score was 0.3% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-55688?

CVE-2026-55688 has a CVSS v3 base score of 4 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N.

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