High
Security advisory
A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-30639
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 06:29 UTC · Revision 1
Source evidence
A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.
osv:CVE-2021-30639
Complete source record
{
"id": "b783fea048a03c1c5e0739e3321d55c7b9b95a5919c41559f3f5035237083a56",
"url": "https://osv.dev/vulnerability/CVE-2021-30639",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2021-30639",
"summary": "A vulnerability in Apache Tomcat allows an attacker to remotely trigger a denial of service. An error introduced as part of a change to improve error handling during non-blocking I/O meant that the error flag associated with the Request object was not reset between requests. This meant that once a non-blocking I/O error occurred, all future requests handled by that request object would fail. Users were able to trigger non-blocking I/O errors, e.g. by dropping a connection, thereby creating the possibility of triggering a DoS. Applications that do not use non-blocking I/O are not exposed to this vulnerability. This issue affects Apache Tomcat 10.0.3 to 10.0.4; 9.0.44; 8.5.64.",
"evidence": "osv:CVE-2021-30639",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2021-30639",
"aliases": [
"BIT-tomcat-2021-30639",
"CVE-2021-30639",
"GHSA-44qp-qhfv-c7f6"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/apache/tomcat",
"type": "GIT",
"events": [
{
"introduced": "c47f86adea090175669df8b2ca04c93050bcaf8c"
},
{
"last_affected": "ec47d24b49bc176f47b786bc96248e94d1823685"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:apache:tomcat:8.5.64:*:*:*:*:*:*:*",
"range": [
{
"introduced": "8.5.64"
},
{
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}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:apache:tomcat:9.0.44:*:*:*:*:*:*:*",
"range": [
{
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},
{
"last_affected": "9.0.44"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:apache:tomcat:10.0.3:*:*:*:*:*:*:*",
"range": [
{
"introduced": "10.0.3"
},
{
"last_affected": "10.0.3"
}
],
"source": "CPE_STRING"
},
{
"cpe": "cpe:2.3:a:apache:tomcat:10.0.4:*:*:*:*:*:*:*",
"range": [
{
"introduced": "10.0.4"
},
{
"last_affected": "10.0.4"
}
],
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}
]
}
}
],
"versions": [
"10.0.3",
"10.0.4",
"8.5.64",
"9.0.44"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-30639.json"
}
}
],
"modified": "2026-10-24T10:30:40.136384269Z",
"provider": "osv",
"references": [
"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cdev.tomcat.apache.org%3E",
"https://lists.apache.org/thread.html/r79a7c019712b39aedf7cf4da9276d80610f04441b2a4f6506cb2daaf%40%3Cusers.tomcat.apache.org%3E",
"https://kc.mcafee.com/corporate/index?page=content&id=SB10366",
"https://lists.apache.org/thread.html/rd84fae1f474597bdf358f5bdc0a5c453c507bd527b83e8be6b5ea3f4%40%3Cannounce.tomcat.apache.org%3E",
"https://security.gentoo.org/glsa/202208-34",
"https://security.netapp.com/advisory/ntap-20210827-0007/",
"https://www.oracle.com/security-alerts/cpujan2022.html"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:a:mcafee:epolicy_orchestrator:*:*:*:*:*:*:*:*"
],
"vendor_product": "mcafee:epolicy_orchestrator",
"extracted_events": [
{
"range": [
{
"fixed": "5.10.0"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
"cpe:2.3:a:oracle:big_data_spatial_and_graph:*:*:*:*:*:*:*:*"
],
"vendor_product": "oracle:big_data_spatial_and_graph",
"extracted_events": [
{
"range": [
{
"fixed": "23.1"
}
],
"source": "CPE_RANGE"
}
]
},
{
"cpes": [
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"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_10:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_1:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_2:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_3:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_4:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_5:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_6:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_7:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_8:*:*:*:*:*:*",
"cpe:2.3:a:mcafee:epolicy_orchestrator:5.10.0:update_9:*:*:*:*:*:*"
],
"vendor_product": "mcafee:epolicy_orchestrator",
"extracted_events": [
{
"range": [
{
"introduced": "5.10.0-NA"
},
{
"last_affected": "5.10.0-NA"
},
{
"introduced": "5.10.0-update_1"
},
{
"last_affected": "5.10.0-update_1"
},
{
"introduced": "5.10.0-update_10"
},
{
"last_affected": "5.10.0-update_10"
},
{
"introduced": "5.10.0-update_2"
},
{
"last_affected": "5.10.0-update_2"
},
{
"introduced": "5.10.0-update_3"
},
{
"last_affected": "5.10.0-update_3"
},
{
"introduced": "5.10.0-update_4"
},
{
"last_affected": "5.10.0-update_4"
},
{
"introduced": "5.10.0-update_5"
},
{
"last_affected": "5.10.0-update_5"
},
{
"introduced": "5.10.0-update_6"
},
{
"last_affected": "5.10.0-update_6"
},
{
"introduced": "5.10.0-update_7"
},
{
"last_affected": "5.10.0-update_7"
},
{
"introduced": "5.10.0-update_8"
},
{
"last_affected": "5.10.0-update_8"
},
{
"introduced": "5.10.0-update_9"
},
{
"last_affected": "5.10.0-update_9"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2021-30639",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 434841,
"published_at": "2021-07-12T15:15:08.333+00:00"
}