CVE-2021-3690

Exp

A flaw was found in Undertow. A buffer leak on the incoming WebSocket PONG message may lead to memory exhaustion. This flaw allows an attacker to cause a denial of service. The highest threat from this vulnerability is availability.

Published: 2022-08-23 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2021-3690 is rated High Exploit Risk (65.4/100): CVSS High severity, with medium exploitation likelihood (EPSS 0.36%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

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

Public exploit references (Exploit-DB) for CVE-2021-3690

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-3690

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 2026-06-06 0.33% 0.36% +0.03%
2 2025-11-21 0.87% 0.33% -0.54%
3 2025-11-18 0.87%

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-3690

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/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:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
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.
3.9 3.6 [email protected]

Weakness enumeration for CVE-2021-3690

GitHub Security Advisory for CVE-2021-3690

GHSA-fj7c-vg2v-ccrm · Severity: high · Ecosystem: maven — Undertow vulnerable to memory exhaustion due to buffer leak

OS Trackers for CVE-2021-3690

vendor priority summary link
debian not yet assigned CVE-2021-3690 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-2021-3690
redhat high https://access.redhat.com/security/cve/CVE-2021-3690
ubuntu medium CVE-2021-3690 medium priority: Ubuntu including 1 source packages (undertow), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): needs-triage 7, ignored 5, DNE 3. https://ubuntu.com/security/CVE-2021-3690

Affected software / configurations for CVE-2021-3690

Vendor Product Version Raw CPE
redhat fuse 1.0 cpe:2.3:a:redhat:fuse:1.0:*:*:*:*:*:*:*
redhat integration_camel_k cpe:2.3:a:redhat:integration_camel_k:-:*:*:*:*:*:*:*
redhat integration_camel_quarkus cpe:2.3:a:redhat:integration_camel_quarkus:-:*:*:*:*:*:*:*
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 < 2.0.40 cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
redhat undertow >= 2.1.0, < 2.2.10 cpe:2.3:a:redhat:undertow:*:*:*:*:*:*:*:*
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:*:*:*:*:*:*:*

References for CVE-2021-3690

cvelogic Threat Intelligence