High
Security advisory
A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35 and 8.5.0 to 8.5.55 could trigger high CPU usage for several seconds. If a sufficient number of such requests were made on concurrent HTTP/2 connections, the server could become unresponsive.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2020-11996
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 04:33 UTC · Revision 1
Source evidence
A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35 and 8.5.0 to 8.5.55 could trigger high CPU usage for several seconds. If a sufficient number of such requests were made on concurrent HTTP/2 connections, the server could become unresponsive.
osv:CVE-2020-11996
Complete source record
{
"id": "7303f3ee49cf80349828ea86dcfa4701488ec3211b1e72773bb66ac5ed654fe8",
"url": "https://osv.dev/vulnerability/CVE-2020-11996",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2020-11996",
"summary": "A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35 and 8.5.0 to 8.5.55 could trigger high CPU usage for several seconds. If a sufficient number of such requests were made on concurrent HTTP/2 connections, the server could become unresponsive.",
"evidence": "osv:CVE-2020-11996",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2020-11996",
"aliases": [
"BIT-tomcat-2020-11996",
"CVE-2020-11996",
"GHSA-53hp-jpwq-2jgq"
],
"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": [
{
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{
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"type": "GIT",
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{
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{
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{
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{
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"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-11996.json"
}
}
],
"modified": "2026-10-24T10:30:19.981280023Z",
"provider": "osv",
"references": [
"https://lists.apache.org/thread.html/r2529016c311ce9485e6f173446d469600fdfbb94dccadfcd9dfdac79%40%3Cusers.tomcat.apache.org%3E",
"https://lists.apache.org/thread.html/r3ea96d8f36dd404acce83df8aeb22a9e807d6c13ca9c5dec72f872cd%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/r5a4f80a6acc6607d61dae424b643b594c6188dd4e1eff04705c10db2%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/r6c29801370a36c1a5159679269777ad0c73276d3015b8bbefea66e5c%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/r74f5a8204efe574cbfcd95b2a16236fe95beb45c4d9fee3dc789dca9%40%3Ccommits.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/r8f3d416c193bc9384a8a7dd368623d441f5fcaff1057115008100561%40%3Ccommits.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c5b11887c922fb1%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/r93ca628ef3a4530dfe5ac49fddc795f0920a4b2a408b57a30926a42b%40%3Ccommits.ofbiz.apache.org%3E",
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"https://lists.apache.org/thread.html/ra7092f7492569b39b04ec0decf52628ba86c51f15efb38f5853e2760%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/rb4ee49ecc4c59620ffd5e66e84a17e526c2c3cfa95d0cd682d90d338%40%3Cnotifications.ofbiz.apache.org%3E",
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"https://lists.apache.org/thread.html/rc80b96b4b96618b2b7461cb90664a428cfd6605eea9f74e51b792542%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/rea65d6ef2e45dd1c45faae83922042732866c7b88fa109b76c83db52%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/ref0339792ac6dac1dba83c071a727ad72380899bde60f6aaad4031b9%40%3Cnotifications.ofbiz.apache.org%3E",
"https://lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe0312ef204a00a2e0%40%3Cannounce.tomcat.apache.org%3E",
"https://lists.debian.org/debian-lts-announce/2020/07/msg00010.html",
"https://security.netapp.com/advisory/ntap-20200709-0002/",
"https://usn.ubuntu.com/4596-1/",
"https://www.debian.org/security/2020/dsa-4727",
"https://www.oracle.com/security-alerts/cpujan2021.html",
"https://www.oracle.com/security-alerts/cpuoct2020.html"
],
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]
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{
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],
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},
{
"cpes": [
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],
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{
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{
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{
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{
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{
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{
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],
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}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2020-11996",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 430156,
"published_at": "2020-06-26T17:15:10.153+00:00"
}