CVE-2025-12543

CRITICALNVD 9.69.6—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.6 under NVD CVSS v3. EPSS exploit probability: 1.2%, top 34% 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
Elevated
9.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.6Exploit: Elevated riskExposed: 0

A fix is available — apply it.

A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without rejection, enabling attackers to poison caches, perform internal network scans, or hijack user sessions.

CVSS v3
9.6
EG Score
9.6(medium)
EG Risk
59(Track*)
EG Risk 59/100SSVC: 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
Severity96% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS PROB
1%
EPSS %ILE
66%
KEV
Not listed

Published

January 7, 2026

Last Modified

August 19, 2026

Advisory Details (12)

Auto-updated Aug 29, 2026
Patch available. Sources: redhat.
redhat Patch Available

Affected: Red Hat Enterprise Linux 7. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:4915
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:3892
redhat Patch Available

Affected: Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:3891
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:3890
redhat Patch Available

Affected: Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:3889
redhat Patch Available

Affected: Red Hat Enterprise Linux 7.

https://access.redhat.com/errata/RHSA-2026:33372
redhat Patch Available

Affected: Red Hat Enterprise Linux 7. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:33371
redhat Patch Available

Affected: Red Hat Enterprise Linux 8.

https://access.redhat.com/errata/RHSA-2026:0386
redhat Patch Available

Affected: Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:0384
redhat Patch Available

Affected: Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:0383
redhat Patch Available

Affected: Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:4917
redhat Patch Available

Affected: Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Important. A Common

https://access.redhat.com/errata/RHSA-2026:4916

Vendor Advisories for CVE-2025-12543(13)

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
ubuntulibundertow-java-doc (1.3.16-1ubuntu0.1~esm1) @ xenial2026-08-19ubuntu
redhateap7-undertow-0:1.4.18-21.SP19_redhat_00001.1.ep7.el72026-06-30redhat
redhateap7-undertow-0:2.0.41-8.SP9_redhat_00001.1.el7eap2026-06-30redhat
redhateap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el7eap2026-03-18redhat
redhatio.undertow/undertow-core:2.2.39.Final-redhat-000012026-03-18redhat
redhateap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el8eap2026-03-18redhat
redhateap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el9eap2026-03-18redhat
redhatundertow-core2026-03-05redhat
redhateap8-undertow-0:2.3.23-1.SP3_redhat_00001.1.el8eap2026-03-05redhat
redhateap8-undertow-0:2.3.23-1.SP3_redhat_00001.1.el9eap2026-03-05redhat
redhateap8-wildfly-javadocs-0:8.1.1-4.GA_redhat_00007.1.el8eap2026-01-08redhat
redhateap8-wildfly-javadocs-0:8.1.1-4.GA_redhat_00007.1.el9eap2026-01-08redhat

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 ... 2.3.8-2 (56 versions)——
Maven(1)
PackageVulnerable rangeFixed inDependents
io.undertow:undertow-core1.0.0.Alpha1 ... 2.2.9.Final (307 versions)2.2.39.Final—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

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 / 50× 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 150 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2025-12543?
CVE-2025-12543 is a critical vulnerability published on January 7, 2026. A flaw was found in the Undertow HTTP server core, which is used in WildFly, JBoss EAP, and other Java applications. The Undertow library fails to properly validate the Host header in incoming HTTP requests.As a result, requests containing malformed or malicious Host headers are processed without…
When was CVE-2025-12543 disclosed?
CVE-2025-12543 was first published in the National Vulnerability Database on January 7, 2026, with the most recent update on August 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-12543 actively exploited?
CVE-2025-12543 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 34.0% of all scored CVEs.
What is the CVSS score of CVE-2025-12543?
CVE-2025-12543 has a CVSS v3 base score of 9.6 (NVD).
How do I remediate CVE-2025-12543?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-12543, 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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