CVE-2021-3859

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 1.3%, top 33% 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, nvd
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

A flaw was found in Undertow that tripped the client-side invocation timeout with certain calls made over HTTP2. This flaw allows an attacker to carry out denial of service attacks.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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
Severity75% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
75%
KEV
Not listed

Published

August 26, 2022

Last Modified

November 21, 2024

References (12)

Vendor Advisories for CVE-2021-3859(6)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(12)

Vendor / EcosystemFixed in / PatchReleasedSource
redhateap7-xml-security-0:2.0.10-2.redhat_00002.1.ep7.el72025-04-28redhat
redhateap7-xml-security-0:2.2.3-2.redhat_00001.1.el7eap2024-11-25redhat
redhatundertow2022-07-07redhat
redhatrh-sso7-keycloak-0:15.0.4-1.redhat_00003.1.el7sso2022-02-07redhat
redhatrh-sso7-keycloak-0:15.0.4-1.redhat_00003.1.el8sso2022-02-07redhat
redhatrh-sso-7/sso74-openj9-openshift-rhel8:7.4-592022-02-02redhat
redhateap7-undertow-0:2.2.13-1.SP2_redhat_00001.1.el7eap2022-02-02redhat
redhatrh-sso-7/sso7-rhel8-operator-bundle:7.5.1-82022-02-02redhat
redhateap7-undertow-0:2.0.41-2.SP2_redhat_00001.1.el8eap2022-02-02redhat
redhatio.undertow/undertow-core:2.2.13.SP2-redhat-000012022-02-02redhat
redhateap7-undertow-0:2.2.13-1.SP2_redhat_00001.1.el8eap2022-02-02redhat
redhatrh-sso-7/sso74-openshift-rhel8:7.4-442022-02-02redhat

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:14(1)
PackageVulnerable rangeFixed inDependents
undertow1.3.11-1 ... 2.2.8-1 (45 versions)2.2.16-1—
Maven(1)
PackageVulnerable rangeFixed inDependents
io.undertow:undertow-core1.0.0.Alpha1 ... 2.2.9.Final (283 versions)2.2.15—

Weakness Classification(2)

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

Additional Vendor Advisories

(10)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 7× in last 7d / 31× 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.

Showing the most recent 100 of 157 total refreshes for this CVE.

  1. 2026-09-07 15:58 UTCEPSS rescore
  2. 2026-09-06 13:45 UTCEPSS rescore
  3. 2026-09-05 15:25 UTCEPSS rescore
  4. 2026-09-05 05:44 UTCOSV refresh
  5. 2026-09-04 13:57 UTCEPSS rescore
  6. 2026-09-04 05:03 UTCEPSS rescore
  7. 2026-09-02 14:09 UTCEPSS rescore
  8. 2026-09-01 13:50 UTCEPSS rescore
  9. 2026-09-01 03:33 UTCEPSS rescore
  10. 2026-08-30 19:14 UTCEPSS rescore
  11. 2026-08-30 19:14 UTCEPSS rescore
  12. 2026-08-30 01:19 UTCEPSS rescore
  13. 2026-08-28 21:37 UTCEPSS rescore
  14. 2026-08-27 14:22 UTCEPSS rescore
  15. 2026-08-26 14:43 UTCEPSS rescore
  16. 2026-08-25 13:46 UTCEPSS rescore
  17. 2026-08-24 14:13 UTCEPSS rescore
  18. 2026-08-23 00:16 UTCEPSS rescore
  19. 2026-08-21 23:46 UTCEPSS rescore
  20. 2026-08-20 22:52 UTCEPSS rescore
  21. 2026-08-20 22:52 UTCEPSS rescore
  22. 2026-08-19 17:01 UTCEPSS rescore
  23. 2026-08-18 16:28 UTCOSV refresh
  24. 2026-08-18 13:45 UTCEPSS rescore
  25. 2026-08-17 13:44 UTCEPSS rescore
Show 75 more
  1. 2026-08-16 14:53 UTCEPSS rescore
  2. 2026-08-16 02:11 UTCEPSS rescore
  3. 2026-08-15 01:27 UTCEPSS rescore
  4. 2026-08-13 21:57 UTCEPSS rescore
  5. 2026-08-12 13:48 UTCEPSS rescore
  6. 2026-08-11 13:38 UTCEPSS rescore
  7. 2026-08-09 13:44 UTCEPSS rescore
  8. 2026-08-08 16:33 UTCEPSS rescore
  9. 2026-08-07 16:24 UTCEPSS rescore
  10. 2026-08-06 13:44 UTCEPSS rescore
  11. 2026-08-05 19:14 UTCEPSS rescore
  12. 2026-08-04 10:34 UTCEPSS rescore
  13. 2026-08-03 11:57 UTCOSV refresh
  14. 2026-08-03 10:33 UTCEPSS rescore
  15. 2026-08-02 02:24 UTCEPSS rescore
  16. 2026-08-01 04:13 UTCEPSS rescore
  17. 2026-07-30 16:25 UTCEPSS rescore
  18. 2026-07-30 01:28 UTCEPSS rescore
  19. 2026-07-28 15:33 UTCEPSS rescore
  20. 2026-07-26 14:52 UTCEPSS rescore
  21. 2026-07-26 14:52 UTCEPSS rescore
  22. 2026-07-25 14:15 UTCEPSS rescore
  23. 2026-07-24 14:15 UTCEPSS rescore
  24. 2026-07-23 14:16 UTCEPSS rescore
  25. 2026-07-23 02:03 UTCEG score recompute
  26. 2026-07-22 22:50 UTCEG score recompute
  27. 2026-07-22 14:06 UTCEPSS rescore
  28. 2026-07-21 15:22 UTCEPSS rescore
  29. 2026-07-21 15:22 UTCEPSS rescore
  30. 2026-07-20 17:05 UTCEPSS rescore
  31. 2026-07-19 14:29 UTCEPSS rescore
  32. 2026-07-19 02:27 UTCEPSS rescore
  33. 2026-07-18 10:02 UTCEPSS rescore
  34. 2026-07-18 10:02 UTCEPSS rescore
  35. 2026-07-16 21:20 UTCOSV refresh
  36. 2026-07-16 17:00 UTCEPSS rescore
  37. 2026-07-16 17:00 UTCEPSS rescore
  38. 2026-07-15 16:55 UTCEPSS rescore
  39. 2026-07-15 16:55 UTCEPSS rescore
  40. 2026-07-15 01:58 UTCEPSS rescore
  41. 2026-07-13 22:27 UTCEPSS rescore
  42. 2026-07-13 22:27 UTCEPSS rescore
  43. 2026-07-13 06:11 UTCEPSS rescore
  44. 2026-07-13 06:11 UTCEPSS rescore
  45. 2026-07-12 05:44 UTCEPSS rescore
  46. 2026-07-11 08:25 UTCEPSS rescore
  47. 2026-07-11 08:25 UTCEPSS rescore
  48. 2026-07-09 19:07 UTCEPSS rescore
  49. 2026-07-08 15:12 UTCEPSS rescore
  50. 2026-07-07 13:43 UTCEPSS rescore
  51. 2026-07-06 16:25 UTCEPSS rescore
  52. 2026-07-06 16:25 UTCEPSS rescore
  53. 2026-07-06 02:21 UTCEPSS rescore
  54. 2026-07-06 02:21 UTCEPSS rescore
  55. 2026-07-05 02:28 UTCEPSS rescore
  56. 2026-07-05 02:28 UTCEPSS rescore
  57. 2026-07-04 06:29 UTCEPSS rescore
  58. 2026-07-04 06:29 UTCEPSS rescore
  59. 2026-07-02 16:57 UTCEPSS rescore
  60. 2026-07-01 15:04 UTCEPSS rescore
  61. 2026-06-30 23:20 UTCEPSS rescore
  62. 2026-06-30 23:20 UTCEPSS rescore
  63. 2026-06-29 14:04 UTCEPSS rescore
  64. 2026-06-28 20:02 UTCOSV refresh
  65. 2026-06-28 14:05 UTCEPSS rescore
  66. 2026-06-28 04:54 UTCEPSS rescore
  67. 2026-06-28 04:54 UTCEPSS rescore
  68. 2026-06-27 03:06 UTCEPSS rescore
  69. 2026-06-27 03:06 UTCEPSS rescore
  70. 2026-06-25 13:48 UTCEPSS rescore
  71. 2026-06-25 13:48 UTCEPSS rescore
  72. 2026-06-24 14:03 UTCEPSS rescore
  73. 2026-06-24 14:03 UTCEPSS rescore
  74. 2026-06-23 21:31 UTCEPSS rescore
  75. 2026-06-23 21:31 UTCEPSS rescore

Frequently asked(5)

What is CVE-2021-3859?
CVE-2021-3859 is a high vulnerability published on August 26, 2022. A flaw was found in Undertow that tripped the client-side invocation timeout with certain calls made over HTTP2. This flaw allows an attacker to carry out denial of service attacks.
When was CVE-2021-3859 disclosed?
CVE-2021-3859 was first published in the National Vulnerability Database on August 26, 2022, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-3859 actively exploited?
CVE-2021-3859 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 25.4% of all scored CVEs.
What is the CVSS score of CVE-2021-3859?
CVE-2021-3859 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2021-3859?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3859, 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.

Dependency Blast Radius

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