CVE-2021-3690

HIGHNVD 7.57.5—

7.5

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.

CVSS v3: 7.5
EG Score: 7.5(medium)
EPSS: 51.2%
KEV: Not listed

Published

August 23, 2022

Last Modified

November 21, 2024

References (8)

secalert@redhathttps://access.redhat.com/security/cve/CVE-2021-3690
secalert@redhathttps://bugzilla.redhat.com/show_bug.cgi?id=1991299
secalert@redhathttps://github.com/undertow-io/undertow/commit/c7e84a0b7efced38506d7d1dfea5902366973877
secalert@redhathttps://issues.redhat.com/browse/UNDERTOW-1935
af854a3a-2127-422b-91ae-364da2661108https://access.redhat.com/security/cve/CVE-2021-3690
af854a3a-2127-422b-91ae-364da2661108https://bugzilla.redhat.com/show_bug.cgi?id=1991299
af854a3a-2127-422b-91ae-364da2661108https://github.com/undertow-io/undertow/commit/c7e84a0b7efced38506d7d1dfea5902366973877
af854a3a-2127-422b-91ae-364da2661108https://issues.redhat.com/browse/UNDERTOW-1935

Vendor Advisories for CVE-2021-3690(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

RHSA-2021:5134
Red Hat Product SecurityCritical
Red Hat Security Advisory: Red Hat Fuse 7.10.0 release and security update

Patch Availability(13)

Vendor / Ecosystem	Fixed in / Patch	Released	Source
redhat	eap7-xml-security-0:2.0.10-2.redhat_00002.1.ep7.el7	2025-04-28	redhat
redhat	undertow	2022-03-23	redhat
redhat	patch	2021-11-23	redhat
redhat	eap7-undertow-0:2.2.9-2.SP1_redhat_00001.1.el7eap	2021-09-23	redhat
redhat	patch	2021-09-23	redhat
redhat	eap7-undertow-0:2.2.9-2.SP1_redhat_00001.1.el8eap	2021-09-23	redhat
redhat	eap7-wildfly-transaction-client-0:1.1.14-2.Final_redhat_00001.1.el7eap	2021-09-08	redhat
redhat	eap7-wildfly-transaction-client-0:1.1.14-2.Final_redhat_00001.1.el6eap	2021-09-08	redhat
redhat	eap7-wildfly-transaction-client-0:1.1.14-2.Final_redhat_00001.1.el8eap	2021-09-08	redhat
redhat	patch	2021-08-18	redhat
redhat	eap7-undertow-0:2.0.38-2.SP2_redhat_00001.1.el8eap	2021-08-18	redhat
redhat	io.undertow/undertow-core:2.2.5.Final-redhat-00001	2021-08-18	redhat
redhat	eap7-undertow-0:2.2.5-2.SP1_redhat_00001.1.el7eap	2021-08-18	redhat

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

(1 across 1 ecosystem)

Maven(1)

Package	Vulnerable range	Fixed in	Dependents
io.undertow:undertow-core	2.2.0.Final ... 2.2.9.Final (10 versions)	2.2.10	—

Weakness Classification(2)

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

Additional Vendor Advisories

(17)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 9× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-05-27 13:39 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-25 16:44 UTCEG score recompute
2026-05-25 16:44 UTCVendor advisory

Frequently asked(5)

What is CVE-2021-3690?

CVE-2021-3690 is a high vulnerability published on August 23, 2022. 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.

When was CVE-2021-3690 disclosed?

CVE-2021-3690 was first published in the National Vulnerability Database on August 23, 2022, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-3690 actively exploited?

CVE-2021-3690 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 51.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-3690?

CVE-2021-3690 has a CVSS v3 base score of 7.5 (NVD).

How do I remediate CVE-2021-3690?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-3690, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-3690

Explore →

Is Your Infrastructure Affected by CVE-2021-3690?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs

CVE-2021-3690

Published

Last Modified

References (8)

Vendor Advisories for CVE-2021-3690(1)

Patch Availability(13)

Affected Packages

Weakness Classification(2)

Additional Vendor Advisories

Data Freshness Timeline

Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-3690?

Same vendor

Same CWE

CVE-2021-3690

📅 Published

🔄 Last Modified

🔗 References (8)

📣 Vendor Advisories for CVE-2021-3690(1)

Patch Availability(13)

Affected Packages

Weakness Classification(2)

Additional Vendor Advisories

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-3690?

🔗 Related CVEs(same vendor + same CWE)

Same vendor

Same CWE

Published

Last Modified

References (8)

Vendor Advisories for CVE-2021-3690(1)

Frequently asked(5)

Related CVEs(same vendor + same CWE)