tomcat9 — security advisory
If an HTTP/2 client connecting to Apache Tomcat 10.0.0-M1 to 10.0.0-M7, 9.0.0.M1 to 9.0.37 or 8.5.0 to 8.5.57 exceeded the agreed maximum number of concurrent streams for a connection (in violation of the HTTP/2 protocol), it was possible that a subsequent request made on that connection could contain HTTP headers - including HTTP/2 pseudo headers - from a previous request rather than the intended headers. This could lead to users seeing responses for unexpected resources.
- Products
- tomcat9
- Affected versions
- Not specified
- Fixed versions
- 9.0.38-1
- CVEs
- CVE-2020-13943
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 28 Oct 2026, 11:08 UTC · Revision 1
Source evidence
If an HTTP/2 client connecting to Apache Tomcat 10.0.0-M1 to 10.0.0-M7, 9.0.0.M1 to 9.0.37 or 8.5.0 to 8.5.57 exceeded the agreed maximum number of concurrent streams for a connection (in violation of the HTTP/2 protocol), it was possible that a subsequent request made on that connection could contain HTTP headers - including HTTP/2 pseudo headers - from a previous request rather than the intended headers. This could lead to users seeing responses for unexpected resources.
osv:DEBIAN-CVE-2020-13943
tomcat9
Fixed versions: 9.0.38-1
tomcat9
Fixed versions: 9.0.38-1
tomcat9
Fixed versions: 9.0.38-1
Complete source record
{
"id": "d4c8cb21807a9bf2473cf37a1f0ada060f02a281ab9c92e5fc89bbfba6276da3",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2020-13943",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2020-13943",
"summary": "If an HTTP/2 client connecting to Apache Tomcat 10.0.0-M1 to 10.0.0-M7, 9.0.0.M1 to 9.0.37 or 8.5.0 to 8.5.57 exceeded the agreed maximum number of concurrent streams for a connection (in violation of the HTTP/2 protocol), it was possible that a subsequent request made on that connection could contain HTTP headers - including HTTP/2 pseudo headers - from a previous request rather than the intended headers. This could lead to users seeing responses for unexpected resources.",
"evidence": "osv:DEBIAN-CVE-2020-13943",
"products": [
{
"name": {
"value": "tomcat9",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "9.0.38-1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "tomcat9",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "9.0.38-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "tomcat9",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "9.0.38-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2020-13943",
"aliases": [
"DEBIAN-CVE-2020-13943"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "9.0.38-1"
}
]
}
],
"package": {
"name": "tomcat9",
"purl": "pkg:deb/debian/tomcat9?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-13943.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "9.0.38-1"
}
]
}
],
"package": {
"name": "tomcat9",
"purl": "pkg:deb/debian/tomcat9?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-13943.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "9.0.38-1"
}
]
}
],
"package": {
"name": "tomcat9",
"purl": "pkg:deb/debian/tomcat9?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-13943.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-09T09:47:35.063619308Z",
"provider": "osv",
"upstream": [
"CVE-2020-13943"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2020-13943"
]
},
"related_cves": [
{
"value": "CVE-2020-13943",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 111686,
"published_at": "2020-10-12T14:15:12.183+00:00"
}