CVE-2021-3629 [Medium] | Denial of Service in Integration

A flaw was found in Undertow. A potential security issue in flow control handling by the browser over http/2 may potentially cause overhead or a denial of service in the server. The highest threat from this vulnerability is availability. This flaw affects Undertow versions prior to 2.0.40.Final and prior to 2.2.11.Final.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-03-15	0.36%	0.29%	-0.07%
2	2025-12-16	0.11%	0.36%	+0.25%
3	2025-11-21	—	0.11%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-03-15

0.36%

0.29%

-0.07%

2025-12-16

0.11%

0.36%

+0.25%

2025-11-21

—

0.11%

—

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]
4.3	2.0	MEDIUM	`AV:N/AC:M/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:M) Exploitation needs some favorable conditions, but not exceptional ones. 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.	8.6	2.9	[email protected]

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]

4.3

2.0

MEDIUM

AV:N/AC:M/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:M): Exploitation needs some favorable conditions, but not exceptional ones.
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.

8.6

2.9

[email protected]

OS Trackers for CVE-2021-3629

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2021-3629 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-2021-3629
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2021-3629
`ubuntu`	medium	CVE-2021-3629 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-2021-3629

Affected software / configurations for CVE-2021-3629

Vendor	Product	Version	Raw CPE
redhat	integration	—	cpe:2.3:a:redhat:integration:-::::text-only:::
redhat	jboss_enterprise_application_platform	—	cpe:2.3:a:redhat:jboss_enterprise_application_platform:-::::text-only:::
redhat	single_sign-on	—	cpe:2.3:a:redhat:single_sign-on:-::::text-only:::
redhat	undertow	< 2.0.40	cpe:2.3:a:redhat:undertow::::::::
redhat	undertow	>= 2.2.0, < 2.2.11	cpe:2.3:a:redhat:undertow::::::::
redhat	wildfly_core	< 17.0	cpe:2.3:a:redhat:wildfly_core::::::::
redhat	jboss_enterprise_application_platform	7.4	cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.4:::::::*
redhat	jboss_enterprise_application_platform	7.3	cpe:2.3:a:redhat:jboss_enterprise_application_platform:7.3:::::::*
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-2021-3629

URL	Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1977362	Issue Tracking Third Party Advisory
https://security.netapp.com/advisory/ntap-20220729-0008/	Third Party Advisory

URL

CVE-2021-3629

Exploit prediction scoring system (EPSS) score for CVE-2021-3629

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3629

Weakness enumeration for CVE-2021-3629

GitHub Security Advisory for CVE-2021-3629

OS Trackers for CVE-2021-3629

Affected software / configurations for CVE-2021-3629

References for CVE-2021-3629