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CVE-2026-28367 Undertow

Affected softwareUndertow
Severity9.1 Critical CVSS 3.1 2 scores
Fixed in2.3.25.Final, 2.2.40.Final
WeaknessCWE-444
Published27 Mar 2026
Updated4 Nov 2026

Description

A flaw was found in Undertow. A remote attacker can exploit this vulnerability by sending \r\r\r as a header block terminator. This can be used for request smuggling with certain proxy servers, such as older versions of Apache Traffic Server and Google Cloud Classic Application Load Balancer, potentially leading to unauthorized access or manipulation of web requests.

Exploitation status

No public exploit

No exploit has been reported in the sources we check.

  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment exploitation: none
  • Indexed PoC none indexed
  • EPSS 0.72% chance in 30 days

Waratek protection

No exploit published

Within Waratek scope. In the sources we check, nobody has published exploit code for this CVE or reported it being exploited.

A public code fix exists: undertow-io/undertow 3ece0bf.

  • Protection none
  • Action unverified
  • Review automated Upstream data
  • Record active
Decided by Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all
Finding This CVE is not listed in CISA KEV or VulnCheck KEV, CISA Vulnrichment records no active exploitation, no reviewed exploit catalogue carries an entry for it, and no GitHub PoC repository for it has 5 or more stars. Nobody has published exploit code worth tracing, so it is not a candidate for a rule ahead of the ones where somebody has; an upstream fix path does exist, so the remediation half of the candidacy still holds. This is a statement about what has been published, not about whether the defect is reachable or serious.
Candidate fix https://bugzilla.redhat.com/show_bug.cgi?id=2443260 : a Red Hat bug: the triage, which links onward to the fix

CVSS

9.1 CRITICAL v3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N 2 metrics

We show the highest score from the newest CVSS version. Scores from different versions can't be compared, and the first score listed is sometimes a 0.0 placeholder.

VersionScoreBandVectorAssignerType
CVSS 3.1 9.1 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N NVD Primary published
CVSS 3.1 8.7 HIGH CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N secalert@redhat.com Secondary

Affected software and releases

Oracle advisories

AdvisoryTypeQuarterProducts Oracle names in its risk matrix
Oracle Critical Patch Update October 2026 ↗ CPU 2026-Q4 Oracle Communications / Alarms, KPI, and Measurements (Undertow) (25.2.200)
Oracle Communications / Install/Upgrade (Undertow) (25.2.200)

Oracle components and versions

FamilyComponentVersions, as Oracle lists themRead as
Oracle Communications Alarms, KPI, and Measurements (Undertow) 25.2.200 25.2.200
Oracle Communications Install/Upgrade (Undertow) 25.2.200 25.2.200

Maven packages

Affected and fixed versions, from OSV.dev
PackageIntroducedFixedLast affected
io.undertow:undertow-core 2.3.0.Final 2.3.25.Final unbounded
io.undertow:undertow-core 0 2.2.40.Final unbounded

Products and versions

10 products, 12 version entries
SourceVendorProductSchemeAffected versions
osv io.undertow undertow-core generic < 2.2.40 · ≥ 2.3.0 and < 2.3.25
nvd redhat build of apache camel - hawtio generic 4.0
nvd redhat build of apache camel for spring boot generic 4.0
nvd redhat data grid generic 8.0
nvd redhat fuse generic 7.0.0
nvd redhat jboss enterprise application platform generic 7.0.0 · 8.0.0
nvd redhat jboss enterprise application platform expansion pack generic any version
nvd redhat process automation generic 7.0
nvd redhat single sign-on generic 7.0
nvd redhat undertow generic any version

References

URLTags
https://bugzilla.redhat.com/show_bug.cgi?id=2443260 bugzilla
https://github.com/undertow-io/undertow/commit/3ece0bf2b2cf5e01db8ca25e41b831e66d3f5961 WEB
https://github.com/undertow-io/undertow/commit/904e26f1be62fb00b440538608a9574839821878 WEB
https://github.com/undertow-io/undertow/commit/c5dc41479e9c3576552d7e98e31bb1c237ae155e WEB
https://access.redhat.com/errata/RHSA-2026:25125 WEB
https://access.redhat.com/errata/RHSA-2026:25126 WEB
https://access.redhat.com/security/cve/CVE-2026-28367 WEB
https://github.com/undertow-io/undertow PACKAGE

Timeline

Published2026-03-27By the CVE Program.
NVD record modified2026-11-04NVD's own last-modified date for this record.