CVE-2021-3597

A flaw was found in undertow. The HTTP2SourceChannel fails to write the final frame under some circumstances, resulting in a denial of service. The highest threat from this vulnerability is availability. This flaw affects Undertow versions prior to 2.0.35.SP1, prior to 2.2.6.SP1, prior to 2.2.7.SP1, prior to 2.0.36.SP1, prior to 2.2.9.Final and prior to 2.0.39.Final.

Published: 2022-05-24 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-3597 is rated Moderate Risk (45.4/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.06%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-3597

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.24% 1.06% +0.82%
2 2025-10-20 0.44% 0.24% -0.20%
3 2025-10-19 — 0.44% —

Full EPSS history (31 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3597

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]
2.6 2.0 LOW
AV:N/AC:H/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:H)
Exploitation requires uncommon or highly specific conditions.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 4.9 2.9 [email protected]

Weakness enumeration for CVE-2021-3597

GitHub Security Advisory for CVE-2021-3597

GHSA-mfhv-gwf8-4m88 · Severity: medium · Ecosystem: maven — undertow Race Condition vulnerability

OS Trackers for CVE-2021-3597

vendor priority summary link
debian not yet assigned CVE-2021-3597 not yet assigned priority: Debian including 1 source packages (undertow), 2 status rows across 2 suites (forky, sid): resolved 2. https://security-tracker.debian.org/tracker/CVE-2021-3597
redhat medium — https://access.redhat.com/security/cve/CVE-2021-3597
ubuntu medium CVE-2021-3597 medium priority: Ubuntu including 1 source packages (undertow), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 7, ignored 6, DNE 3. https://ubuntu.com/security/CVE-2021-3597

Affected software / configurations for CVE-2021-3597

Vendor Product Version Raw CPE
redhat fuse 1.0 cpe:2.3:a:redhat:fuse:1.0:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform — cpe:2.3:a:redhat:jboss_enterprise_application_platform:-:*:*:*:text-only:*:*:*
redhat openshift_application_runtimes — cpe:2.3:a:redhat:openshift_application_runtimes:-:*:*:*:text-only:*:*:*
redhat single_sign-on — cpe:2.3:a:redhat:single_sign-on:-:*:*:*:text-only:*:*:*
redhat undertow < 2.0.35 cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
redhat undertow >= 2.2.0, < 2.2.6 cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
redhat undertow 2.0.35 cpe:2.3:a:redhat:undertow:2.0.35:-:*:*:*:*:*:*
redhat undertow 2.0.36 cpe:2.3:a:redhat:undertow:2.0.36:-:*:*:*:*:*:*
redhat undertow 2.0.39 cpe:2.3:a:redhat:undertow:2.0.39:-:*:*:*:*:*:*
redhat undertow 2.2.6 cpe:2.3:a:redhat:undertow:2.2.6:-:*:*:*:*:*:*
redhat undertow 2.2.7 cpe:2.3:a:redhat:undertow:2.2.7:-:*:*:*:*:*:*
redhat undertow 2.2.9 cpe:2.3:a:redhat:undertow:2.2.9:-:*:*:*:*:*:*
redhat jboss_enterprise_application_platform 7.3 cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.3:*:*:*:*:*:*:*
redhat jboss_enterprise_application_platform 7.4 cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.4:*:*:*:*:*:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:linux:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
netapp active_iq_unified_manager — cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:*
netapp oncommand_insight — cpe:2.3:a:netapp:oncommand_insight:-:*:*:*:*:*:*:*
netapp oncommand_workflow_automation — cpe:2.3:a:netapp:oncommand_workflow_automation:-:*:*:*:*:*:*:*

References for CVE-2021-3597

cvelogic Threat Intelligence