CVE-2026-55688

MEDIUMPre-NVD 4.04.0—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.0 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
4.0
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.0Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
4.0
EG Score
4.0(medium)
EPSS
7.6%
KEV
Not listed

Published

July 1, 2026

Last Modified

July 2, 2026

Advisory Details (2)

Auto-updated Jul 3, 2026
Patch available. Sources: github_pr, github.
github Patch Available

Cookie stored for an unrelated domain (cookie tossing) in AsyncHttpClient ThreadSafeCookieStore · Advisory · AsyncHttpClient/async-http-client · GitHub

Affected: 3.0.11 and 2.16.0

https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-m452-q8c9-rg2f
github_pr Patch Available

reject set-cookie domain that doesn't match the request host

Patch available: AsyncHttpClient/async-http-client async-http-client-project-3.0.11 (PR #2196 merged 2026-06-14)

https://github.com/AsyncHttpClient/async-http-client/pull/2196

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 19× in last 7d / 26× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-11 08:27 UTCEPSS rescore
  3. 2026-07-11 00:41 UTCEG score recompute
  4. 2026-07-10 02:44 UTCEG score recompute
  5. 2026-07-09 19:10 UTCEPSS rescore
  6. 2026-07-09 19:10 UTCEPSS rescore
  7. 2026-07-09 04:46 UTCEG score recompute
  8. 2026-07-08 15:16 UTCEPSS rescore
  9. 2026-07-08 15:16 UTCEPSS rescore
  10. 2026-07-08 06:52 UTCEG score recompute
  11. 2026-07-07 13:46 UTCEPSS rescore
  12. 2026-07-07 13:46 UTCEPSS rescore
  13. 2026-07-07 08:59 UTCEG score recompute
  14. 2026-07-06 10:57 UTCEG score recompute
  15. 2026-07-06 02:23 UTCEPSS rescore
  16. 2026-07-06 02:23 UTCEPSS rescore
  17. 2026-07-05 12:46 UTCEG score recompute
  18. 2026-07-05 02:31 UTCEPSS rescore
  19. 2026-07-05 02:30 UTCEPSS rescore
  20. 2026-07-04 14:51 UTCEG score recompute
  21. 2026-07-04 06:31 UTCEPSS rescore
  22. 2026-07-04 06:31 UTCEPSS rescore
  23. 2026-07-03 16:58 UTCEG score recompute
  24. 2026-07-02 19:03 UTCEG score recompute
  25. 2026-07-01 21:09 UTCEG score recompute
Show 1 more
  1. 2026-07-01 21:08 UTCNVD updatefirst tracked

Frequently asked(5)

What is CVE-2026-55688?
CVE-2026-55688 is a medium vulnerability published on July 1, 2026. 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…
When was CVE-2026-55688 disclosed?
CVE-2026-55688 was first published in the National Vulnerability Database on July 1, 2026, with the most recent update on July 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55688 actively exploited?
CVE-2026-55688 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 7.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-55688?
CVE-2026-55688 has a CVSS v3 base score of 4.0 (NVD).
How do I remediate CVE-2026-55688?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55688, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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