CVE-2026-28369

CRITICALNVD 9.18.7▼
EchelonGraph scoreMEDIUM confidence

Score 8.7 from GitHub Security Advisory (severity: HIGH) published 2026-03-27. NVD baseline CVSS 9.1; sources differ by 0.4.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 9.1Exploit: NoneExposed: 0

A fix is available — apply it.

A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or more spaces, it incorrectly processes the request by stripping these leading spaces. This behavior, which violates HTTP standards, can be exploited by a remote attacker to perform request smuggling. Request smuggling allows an attacker to bypass security mechanisms, access restricted information, or manipulate web caches, potentially leading to unauthorized actions or data exposure.

CVSS v3
9.1
EG Score
8.7(medium)
EPSS
47.8%
KEV
Not listed

Published

March 27, 2026

Last Modified

June 10, 2026

Advisory Details (4)

Auto-updated Jun 11, 2026
Patch available. Sources: redhat.
redhat Patch Available

2443262 – (CVE-2026-28369) CVE-2026-28369 undertow: Undertow: Request Smuggling via Malformed HTTP Request Headers

https://bugzilla.redhat.com/show_bug.cgi?id=2443262
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-28369
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:25126
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:25125

Vendor Advisories for CVE-2026-28369(3)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
redhateap8-wildfly-0:8.1.6-7.GA_redhat_00010.1.el9eap2026-06-10redhat
redhatundertow-core2026-06-10redhat
mavenio.undertow:undertow-parent—ghsa

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-parent1.0.0.Alpha1 ... 2.3.9.Final (335 versions)——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 45× 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. 2026-07-06 16:27 UTCEPSS rescore
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 02:23 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-05 02:30 UTCEPSS rescore
  6. 2026-07-04 06:31 UTCEPSS rescore
  7. 2026-07-01 15:06 UTCEPSS rescore
  8. 2026-06-30 23:22 UTCEPSS rescore
  9. 2026-06-30 23:22 UTCEPSS rescore
  10. 2026-06-29 14:06 UTCEPSS rescore
  11. 2026-06-28 14:07 UTCEPSS rescore
  12. 2026-06-28 14:07 UTCEPSS rescore
  13. 2026-06-28 04:56 UTCEPSS rescore
  14. 2026-06-28 04:56 UTCEPSS rescore
  15. 2026-06-27 03:08 UTCEPSS rescore
  16. 2026-06-25 13:49 UTCEPSS rescore
  17. 2026-06-25 13:49 UTCEPSS rescore
  18. 2026-06-24 14:05 UTCEPSS rescore
  19. 2026-06-24 14:05 UTCEPSS rescore
  20. 2026-06-23 21:33 UTCEPSS rescore
  21. 2026-06-23 21:32 UTCEPSS rescore
  22. 2026-06-22 14:25 UTCEPSS rescore
  23. 2026-06-22 14:25 UTCEPSS rescore
  24. 2026-06-21 14:56 UTCEPSS rescore
  25. 2026-06-21 14:56 UTCEPSS rescore
Show 20 more
  1. 2026-06-21 01:59 UTCEPSS rescore
  2. 2026-06-21 01:59 UTCEPSS rescore
  3. 2026-06-19 19:25 UTCEPSS rescore
  4. 2026-06-19 19:25 UTCEPSS rescore
  5. 2026-06-18 17:52 UTCEPSS rescore
  6. 2026-06-17 17:53 UTCEPSS rescore
  7. 2026-06-17 17:53 UTCEPSS rescore
  8. 2026-06-16 17:52 UTCEPSS rescore
  9. 2026-06-15 17:48 UTCEPSS rescore
  10. 2026-06-14 23:18 UTCEPSS rescore
  11. 2026-06-13 23:00 UTCEPSS rescore
  12. 2026-06-12 23:12 UTCEPSS rescore
  13. 2026-06-12 23:12 UTCEPSS rescore
  14. 2026-06-11 23:01 UTCEG score recompute
  15. 2026-06-11 23:01 UTCVendor advisory
  16. 2026-06-11 23:01 UTCGHSA enrichment
  17. 2026-06-11 14:00 UTCEPSS rescore
  18. 2026-06-10 23:00 UTCEG score recompute
  19. 2026-06-10 23:00 UTCGHSA enrichment
  20. 2026-06-10 22:59 UTCNVD updatefirst tracked

Related CVEs(same product + same vendor + same CWE)

Same product

2 shown

maven:io.undertow:undertow-parent

Frequently asked(5)

What is CVE-2026-28369?
CVE-2026-28369 is a critical vulnerability published on March 27, 2026. A flaw was found in Undertow. When Undertow receives an HTTP request where the first header line starts with one or more spaces, it incorrectly processes the request by stripping these leading spaces. This behavior, which violates HTTP standards, can be exploited by a remote attacker to perform…
When was CVE-2026-28369 disclosed?
CVE-2026-28369 was first published in the National Vulnerability Database on March 27, 2026, with the most recent update on June 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-28369 actively exploited?
CVE-2026-28369 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 47.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-28369?
CVE-2026-28369 has a CVSS v3 base score of 9.1 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.7.
How do I remediate CVE-2026-28369?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-28369, 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-2026-28369

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