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: 0.3%, top 75% 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
Trending — 3 sources updated this week
4.0EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.0Exploit: None knownExposed: 0

A fix is available — apply it.

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)
EG Risk
18(Track)
EG Risk 18/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity40% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
25%
KEV
Not listed

Published

July 1, 2026

Last Modified

August 6, 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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibasync-http-client-java (2.12.3-1ubuntu0.24.04.1) @ noble2026-08-25ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(2 across 2 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
async-http-client2.12.2-12.12.2-1+deb11u1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
async-http-client2.12.3-1——

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 9× in last 7d / 51× 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. 2026-08-25 13:49 UTCEPSS rescore
  2. 2026-08-25 02:04 UTCEG score recompute
  3. 2026-08-25 02:04 UTCVendor advisory
  4. 2026-08-23 04:51 UTCEG score recompute
  5. 2026-08-23 00:19 UTCEPSS rescore
  6. 2026-08-22 06:58 UTCEG score recompute
  7. 2026-08-21 23:49 UTCEPSS rescore
  8. 2026-08-20 04:36 UTCEG score recompute
  9. 2026-08-19 17:04 UTCEPSS rescore
  10. 2026-08-18 22:31 UTCEG score recompute
  11. 2026-08-18 13:48 UTCEPSS rescore
  12. 2026-08-17 23:19 UTCEG score recompute
  13. 2026-08-17 13:47 UTCEPSS rescore
  14. 2026-08-16 23:35 UTCEG score recompute
  15. 2026-08-16 14:56 UTCEPSS rescore
  16. 2026-08-16 02:14 UTCEPSS rescore
  17. 2026-08-15 03:48 UTCEG score recompute
  18. 2026-08-15 01:30 UTCEPSS rescore
  19. 2026-08-14 05:54 UTCEG score recompute
  20. 2026-08-13 22:00 UTCEPSS rescore
  21. 2026-08-13 08:01 UTCEG score recompute
  22. 2026-08-12 13:51 UTCEPSS rescore
  23. 2026-08-12 10:08 UTCEG score recompute
  24. 2026-08-11 12:13 UTCEG score recompute
  25. 2026-08-11 00:00 UTCEPSS rescore
Show 64 more
  1. 2026-08-09 16:26 UTCEG score recompute
  2. 2026-08-09 13:46 UTCEPSS rescore
  3. 2026-08-08 18:33 UTCEG score recompute
  4. 2026-08-08 16:37 UTCEPSS rescore
  5. 2026-08-07 20:39 UTCEG score recompute
  6. 2026-08-06 22:45 UTCEG score recompute
  7. 2026-08-06 15:52 UTCEG score recompute
  8. 2026-08-06 13:47 UTCEPSS rescore
  9. 2026-08-05 19:17 UTCEPSS rescore
  10. 2026-08-04 20:06 UTCEG score recompute
  11. 2026-08-04 15:10 UTCEPSS rescore
  12. 2026-08-04 10:39 UTCEPSS rescore
  13. 2026-08-03 22:11 UTCEG score recompute
  14. 2026-08-03 10:36 UTCEPSS rescore
  15. 2026-08-03 00:18 UTCEG score recompute
  16. 2026-08-02 02:27 UTCEPSS rescore
  17. 2026-08-01 04:31 UTCEG score recompute
  18. 2026-08-01 04:16 UTCEPSS rescore
  19. 2026-07-31 06:35 UTCEG score recompute
  20. 2026-07-30 16:28 UTCEPSS rescore
  21. 2026-07-30 08:39 UTCEG score recompute
  22. 2026-07-30 01:30 UTCEPSS rescore
  23. 2026-07-29 08:31 UTCEG score recompute
  24. 2026-07-28 15:37 UTCEPSS rescore
  25. 2026-07-28 09:09 UTCEG score recompute
  26. 2026-07-27 11:08 UTCEG score recompute
  27. 2026-07-26 14:54 UTCEPSS rescore
  28. 2026-07-26 13:13 UTCEG score recompute
  29. 2026-07-25 14:18 UTCEPSS rescore
  30. 2026-07-24 14:18 UTCEPSS rescore
  31. 2026-07-23 14:18 UTCEPSS rescore
  32. 2026-07-23 03:20 UTCEG score recompute
  33. 2026-07-22 14:08 UTCEPSS rescore
  34. 2026-07-21 15:25 UTCEPSS rescore
  35. 2026-07-20 17:08 UTCEPSS rescore
  36. 2026-07-19 14:31 UTCEPSS rescore
  37. 2026-07-19 14:31 UTCEPSS rescore
  38. 2026-07-19 02:29 UTCEPSS rescore
  39. 2026-07-18 10:04 UTCEPSS rescore
  40. 2026-07-16 17:03 UTCEPSS rescore
  41. 2026-07-15 16:57 UTCEPSS rescore
  42. 2026-07-15 16:57 UTCEPSS rescore
  43. 2026-07-15 02:00 UTCEPSS rescore
  44. 2026-07-15 02:00 UTCEPSS rescore
  45. 2026-07-13 22:31 UTCEPSS rescore
  46. 2026-07-13 06:13 UTCEPSS rescore
  47. 2026-07-13 06:13 UTCEPSS rescore
  48. 2026-07-12 05:46 UTCEPSS rescore
  49. 2026-07-11 08:27 UTCEPSS rescore
  50. 2026-07-11 08:27 UTCEPSS rescore
  51. 2026-07-09 19:10 UTCEPSS rescore
  52. 2026-07-09 19:10 UTCEPSS rescore
  53. 2026-07-08 15:16 UTCEPSS rescore
  54. 2026-07-08 15:16 UTCEPSS rescore
  55. 2026-07-07 13:46 UTCEPSS rescore
  56. 2026-07-07 13:46 UTCEPSS rescore
  57. 2026-07-06 02:23 UTCEPSS rescore
  58. 2026-07-06 02:23 UTCEPSS rescore
  59. 2026-07-05 02:31 UTCEPSS rescore
  60. 2026-07-05 02:30 UTCEPSS rescore
  61. 2026-07-04 06:31 UTCEPSS rescore
  62. 2026-07-04 06:31 UTCEPSS rescore
  63. 2026-07-01 21:09 UTCEG score recompute
  64. 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 August 6, 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 0% probability of exploitation in the next 30 days, which ranks it in the top 74.6% of all scored CVEs.
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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