CVE-2025-12543

CRITICALNVD 9.69.6—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.6 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 84% 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
9.6
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.6Exploit: NoneExposed: 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)
EPSS
64.1%
KEV
Not listed

Published

January 7, 2026

Last Modified

July 15, 2026

Advisory Details (10)

Auto-updated Jun 25, 2026
Patch available. Sources: redhat.
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
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 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

Vendor Advisories for CVE-2025-12543(6)

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

Patch Availability(10)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibundertow-java-doc (1.3.16-1ubuntu0.1~esm1) @ xenial2026-05-29ubuntu
redhatio.undertow/undertow-core:2.2.39.Final-redhat-000012026-03-18redhat
redhateap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el7eap2026-03-18redhat
redhateap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el9eap2026-03-18redhat
redhateap7-wildfly-0:7.4.24-4.GA_redhat_00002.1.el8eap2026-03-18redhat
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
redhatundertow-core2026-03-05redhat
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

(1 across 1 ecosystem)
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

(7)

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 12× in last 7d / 44× 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. 2026-07-16 17:02 UTCEPSS rescore
  2. 2026-07-16 17:02 UTCEPSS rescore
  3. 2026-07-15 16:57 UTCEPSS rescore
  4. 2026-07-15 16:57 UTCEPSS rescore
  5. 2026-07-15 01:59 UTCEPSS rescore
  6. 2026-07-15 01:59 UTCEPSS rescore
  7. 2026-07-13 22:29 UTCEPSS rescore
  8. 2026-07-13 22:29 UTCEPSS rescore
  9. 2026-07-12 05:46 UTCEPSS rescore
  10. 2026-07-12 05:45 UTCEPSS rescore
  11. 2026-07-11 08:26 UTCEPSS rescore
  12. 2026-07-11 08:26 UTCEPSS rescore
  13. 2026-07-09 19:09 UTCEPSS rescore
  14. 2026-07-08 15:14 UTCEPSS rescore
  15. 2026-07-07 13:45 UTCEPSS rescore
  16. 2026-07-06 16:26 UTCEPSS rescore
  17. 2026-07-06 06:02 UTCOSV refresh
  18. 2026-07-06 02:22 UTCEPSS rescore
  19. 2026-07-06 02:22 UTCEPSS rescore
  20. 2026-07-05 02:30 UTCEPSS rescore
  21. 2026-07-04 06:30 UTCEPSS rescore
  22. 2026-07-01 15:06 UTCEPSS rescore
  23. 2026-06-30 23:21 UTCEPSS rescore
  24. 2026-06-29 14:06 UTCEPSS rescore
  25. 2026-06-28 04:55 UTCEPSS rescore
Show 48 more
  1. 2026-06-27 03:08 UTCEPSS rescore
  2. 2026-06-27 03:08 UTCEPSS rescore
  3. 2026-06-25 13:49 UTCEPSS rescore
  4. 2026-06-25 13:49 UTCEPSS rescore
  5. 2026-06-24 14:04 UTCEPSS rescore
  6. 2026-06-24 14:04 UTCEPSS rescore
  7. 2026-06-23 21:32 UTCEPSS rescore
  8. 2026-06-22 14:25 UTCEPSS rescore
  9. 2026-06-22 14:25 UTCEPSS rescore
  10. 2026-06-21 14:56 UTCEPSS rescore
  11. 2026-06-21 14:56 UTCEPSS rescore
  12. 2026-06-21 01:59 UTCEPSS rescore
  13. 2026-06-21 01:59 UTCEPSS rescore
  14. 2026-06-19 19:25 UTCEPSS rescore
  15. 2026-06-19 19:25 UTCEPSS rescore
  16. 2026-06-18 17:52 UTCEPSS rescore
  17. 2026-06-18 17:52 UTCEPSS rescore
  18. 2026-06-17 17:52 UTCEPSS rescore
  19. 2026-06-17 17:44 UTCOSV refresh
  20. 2026-06-16 17:52 UTCEPSS rescore
  21. 2026-06-15 17:48 UTCEPSS rescore
  22. 2026-06-14 23:17 UTCEPSS rescore
  23. 2026-06-13 22:59 UTCEPSS rescore
  24. 2026-06-13 22:59 UTCEPSS rescore
  25. 2026-06-12 23:11 UTCEPSS rescore
  26. 2026-06-11 13:59 UTCEPSS rescore
  27. 2026-06-10 22:18 UTCEPSS rescore
  28. 2026-06-10 13:21 UTCEPSS rescore
  29. 2026-06-08 14:16 UTCEPSS rescore
  30. 2026-06-08 14:16 UTCEPSS rescore
  31. 2026-06-07 15:24 UTCEPSS rescore
  32. 2026-06-06 13:47 UTCEPSS rescore
  33. 2026-06-06 13:47 UTCEPSS rescore
  34. 2026-06-05 22:46 UTCEPSS rescore
  35. 2026-06-05 22:46 UTCEPSS rescore
  36. 2026-06-05 06:10 UTCEPSS rescore
  37. 2026-06-05 06:10 UTCEPSS rescore
  38. 2026-06-04 13:11 UTCEPSS rescore
  39. 2026-06-04 13:11 UTCEPSS rescore
  40. 2026-06-01 13:51 UTCEPSS rescore
  41. 2026-06-01 13:51 UTCEPSS rescore
  42. 2026-05-31 22:30 UTCEPSS rescore
  43. 2026-05-31 22:30 UTCEPSS rescore
  44. 2026-05-31 00:16 UTCEPSS rescore
  45. 2026-05-31 00:16 UTCEPSS rescore
  46. 2026-05-29 16:34 UTCEG score recompute
  47. 2026-05-29 16:34 UTCVendor advisory
  48. 2026-05-29 13:44 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

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 July 15, 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 64.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-12543

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