CVE-2026-28369

CRITICALNVD 9.19.1
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.7% (53rd percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 8.7 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-03-27) is not newer than that change (2026-11-04), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2026-16698 (ENISA EUVD) · GHSA-vqqj-9cmv-hx43 (GitHub Security Advisories)Source: ENISA EUVD

9.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 9.1Exploit: None knownExposed services: Not assessed

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
9.1CRITICALmedium confidence
EG Risk
41
EG Risk 41/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity91% × 45%
Impact severity (EG Severity): CVSS 9.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.7% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.7%
EPSS %ILE
53rd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.1): severity, escalated by confirmed exploitation. This CVE's 9.1 is its impact severity (EG Severity), not escalated.

EG Severity
9.1 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.7% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-12). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

March 27, 2026

Last Modified

November 4, 2026

Advisory Details (4)

Auto-updated Sep 16, 2026
Patch available. Sources: redhat.
Red HatMentions a patch (unverified)

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
Red HatMentions a patch (unverified)

CVE-2026-28369 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-28369
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:25126
Red HatMentions a patch (unverified)
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(4)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatio.undertow/undertow-core:2.3.24.SP2-redhat-000012026-06-10redhat
redhateap8-wildfly-0:8.1.6-7.GA_redhat_00010.1.el9eap2026-06-10redhat
mavenio.undertow:undertow-core @ 2.2.40.Final (fixes < 2.2.40.Final)—ghsa
mavenio.undertow:undertow-core @ 2.3.25.Final (fixes >= 2.3.0.Final, < 2.3.25.Final)—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

(3 across 2 ecosystems)
Maven(2)
PackageVulnerable rangeFix by version rangeDependents
io.undertow:undertow-core2.3.0.Final ... 2.3.9.Final (25 versions)
  • every version up to 2.2.40.Final: fixed in 2.2.40.Final
  • 2.3.0.Final up to 2.3.25.Final: fixed in 2.3.25.Final
—
io.undertow:undertow-parent1.0.0.Alpha1 ... 2.3.9.Final (336 versions)
  • every version through 2.3.23.Final: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
undertow1.3.11-1 ... 2.3.8-2 (56 versions)
  • every version on: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 22× in last 7d / 94× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 371 rows on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 271 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-13 16:51 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  2. 2026-11-13 11:57 UTCEchelonGraph re-scored
  3. 2026-11-13 11:57 UTCVendor advisory
  4. 2026-11-13 11:57 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  5. 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  6. 2026-11-12 13:14 UTCEchelonGraph re-scored
  7. 2026-11-12 13:14 UTCVendor advisory
  8. 2026-11-12 13:14 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  9. 2026-11-11 16:39 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  10. 2026-11-11 14:30 UTCEchelonGraph re-scored
  11. 2026-11-11 14:30 UTCVendor advisory
  12. 2026-11-11 14:30 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  13. 2026-11-10 16:43 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  14. 2026-11-10 15:48 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  15. 2026-11-09 17:04 UTCEchelonGraph re-scored
  16. 2026-11-09 17:04 UTCVendor advisory
  17. 2026-11-09 17:04 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  18. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  19. 2026-11-08 18:22 UTCEchelonGraph re-scored
  20. 2026-11-08 18:22 UTCVendor advisory
  21. 2026-11-08 18:22 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  22. 2026-11-08 16:39 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  23. 2026-11-07 19:39 UTCEchelonGraph re-scored
  24. 2026-11-07 19:39 UTCVendor advisory
  25. 2026-11-07 19:39 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
Show 75 more
  1. 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  2. 2026-11-06 20:57 UTCEchelonGraph re-scored
  3. 2026-11-06 20:57 UTCVendor advisory
  4. 2026-11-06 20:57 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  5. 2026-11-06 16:37 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  6. 2026-11-05 22:14 UTCEchelonGraph re-scored
  7. 2026-11-05 22:14 UTCVendor advisory
  8. 2026-11-05 22:14 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  9. 2026-11-05 16:37 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  10. 2026-11-04 23:26 UTCVendor advisory
  11. 2026-11-04 23:26 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  12. 2026-11-04 22:26 UTCEchelonGraph re-scored
  13. 2026-11-04 22:26 UTCVendor advisory
  14. 2026-11-04 22:26 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  15. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  16. 2026-11-04 10:17 UTCEchelonGraph re-scored
  17. 2026-11-04 10:17 UTCVendor advisory
  18. 2026-11-04 10:17 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  19. 2026-11-03 16:47 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  20. 2026-11-03 11:31 UTCEchelonGraph re-scored
  21. 2026-11-03 11:31 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  22. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  23. 2026-11-02 12:47 UTCEchelonGraph re-scored
  24. 2026-11-02 12:47 UTCVendor advisory
  25. 2026-11-02 12:47 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  26. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  27. 2026-11-01 14:04 UTCEchelonGraph re-scored
  28. 2026-11-01 14:04 UTCVendor advisory
  29. 2026-11-01 14:04 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  30. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  31. 2026-10-31 15:20 UTCVendor advisory
  32. 2026-10-31 15:20 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  33. 2026-10-30 16:38 UTCEchelonGraph re-scored
  34. 2026-10-30 16:38 UTCVendor advisory
  35. 2026-10-30 16:38 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  36. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  37. 2026-10-29 17:55 UTCEchelonGraph re-scored
  38. 2026-10-29 17:55 UTCVendor advisory
  39. 2026-10-29 17:55 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  40. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  41. 2026-10-28 19:10 UTCEchelonGraph re-scored
  42. 2026-10-28 19:10 UTCVendor advisory
  43. 2026-10-28 19:10 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  44. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  45. 2026-10-27 20:09 UTCEchelonGraph re-scored
  46. 2026-10-27 20:09 UTCVendor advisory
  47. 2026-10-27 20:09 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  48. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  49. 2026-10-26 21:26 UTCEchelonGraph re-scored
  50. 2026-10-26 21:26 UTCVendor advisory
  51. 2026-10-26 21:26 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  52. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  53. 2026-10-26 14:17 UTCEchelonGraph re-scored
  54. 2026-10-26 14:17 UTCVendor advisory
  55. 2026-10-26 14:17 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  56. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  57. 2026-10-25 15:04 UTCVendor advisory
  58. 2026-10-25 15:04 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  59. 2026-10-25 14:38 UTCEchelonGraph re-scored
  60. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.9% · 59th percentile
  61. 2026-10-24 16:20 UTCVendor advisory
  62. 2026-10-24 16:20 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  63. 2026-10-23 17:37 UTCEchelonGraph re-scored
  64. 2026-10-23 17:37 UTCVendor advisory
  65. 2026-10-23 17:37 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  66. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  67. 2026-10-22 18:55 UTCEchelonGraph re-scored
  68. 2026-10-22 18:55 UTCVendor advisory
  69. 2026-10-22 18:55 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  70. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  71. 2026-10-21 20:12 UTCEchelonGraph re-scored
  72. 2026-10-21 20:12 UTCVendor advisory
  73. 2026-10-21 20:12 UTCGHSA enrichmentGHSA-vqqj-9cmv-hx43 · GitHub severity HIGH · GitHub CVSS 8.7
  74. 2026-10-21 16:32 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  75. 2026-10-20 21:30 UTCEchelonGraph re-scored

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Frequently asked(5)

What is CVE-2026-28369?
CVE-2026-28369 is a critical-severity vulnerability; its CVE record was 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 made public?
CVE-2026-28369 was made public on August 27, 2025: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on March 27, 2026. EchelonGraph's copy of the record carries a last-modified date of November 4, 2026; the record at its source may have been updated since.
Is CVE-2026-28369 actively exploited?
CVE-2026-28369 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (53rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-28369?
CVE-2026-28369 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-28369?
A fix for CVE-2026-28369 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-28369 are linked in the Vendor Advisories panel on this page.

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