HighFix available
golang-1.19, golang-1.24 and 2 more products — security advisory
When http.Transport sends an HTTP/1 CONNECT request with a non-empty Request.Body, it writes the body directly to the connection without framing after the request headers. If the server rejects the CONNECT request with a non-2xx keep-alive response, Transport returns the connection to the idle pool. Because CONNECT requests do not have a request body, the server may interpret the trailing body bytes as a subsequent pipelined HTTP/1.1 request on the connection, leaving the pooled connection desynchronized and causing the next caller that reuses it to read the response to the injected request. In reverse proxies (including httputil.ReverseProxy) that forward CONNECT requests through a shared Transport, this can lead to cross-user response poisoning.
- Products
- golang-1.19, golang-1.24, golang-1.26, golang-1.27
- Affected versions
- 1.19.10-1, 1.19.10-2, 1.19.11-1, 1.19.12-1, 1.19.12-2, 1.19.12-2~bpo11+1, 1.19.12-2~bpo12+1, 1.19.13-1, 1.19.13-1~bpo11+1, 1.19.13-1~bpo12+1, 1.19.8-2, 1.19.9-1, 1.24.12-1, 1.24.13-1, 1.24.13-2, 1.24.4-1, 1.24.4-2, 1.24.4-3, 1.24.4-4, 1.24.7-1, 1.24.8-1, 1.24.9-1, 1.26.0-1, 1.26.1-1, 1.26.2-1, 1.26.2-2, 1.26.2-3, 1.26.3-1, 1.26.3-1~bpo13+1, 1.26.3-2, 1.26.3-2~bpo13+1, 1.26.4-1, 1.26.4-1~bpo13+1, 1.26.5-1, 1.26.5-1~bpo13+1, 1.26.6-1, 1.26.6-2, 1.26.7-1, 1.26.7-1~bpo13+1, 1.26.8-1, 1.26.8-1~bpo13+1, 1.26.8-2, 1.26~rc2-1, 1.26~rc3-1, 1.26~rc3-2, 1.27.0-1, 1.27.0-1~bpo13+1, 1.27.1-1, 1.27.1-2, 1.27.1-2~bpo13+1, 1.27~rc1-1, 1.27~rc2-1, 1.27~rc3-1
- Fixed versions
- 1.26.9-1, 1.27.2-1
- CVEs
- CVE-2026-56866
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 30 Oct 2026, 06:33 UTC · Revision 1
Source evidence
When http.Transport sends an HTTP/1 CONNECT request with a non-empty Request.Body, it writes the body directly to the connection without framing after the request headers. If the server rejects the CONNECT request with a non-2xx keep-alive response, Transport returns the connection to the idle pool. Because CONNECT requests do not have a request body, the server may interpret the trailing body bytes as a subsequent pipelined HTTP/1.1 request on the connection, leaving the pooled connection desynchronized and causing the next caller that reuses it to read the response to the injected request. In reverse proxies (including httputil.ReverseProxy) that forward CONNECT requests through a shared Transport, this can lead to cross-user response poisoning.
osv:DEBIAN-CVE-2026-56866
golang-1.19
Fixed versions: Not specified
golang-1.24
Fixed versions: Not specified
golang-1.26
Fixed versions: 1.26.9-1
golang-1.27
Fixed versions: 1.27.2-1
Complete source record
{
"id": "4780fdc930dd6fc1a7a95647f30a3ef90bdc1b6b4e79bf161a75df2268b9d487",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-56866",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2026-56866",
"summary": "When http.Transport sends an HTTP/1 CONNECT request with a non-empty Request.Body, it writes the body directly to the connection without framing after the request headers. If the server rejects the CONNECT request with a non-2xx keep-alive response, Transport returns the connection to the idle pool. Because CONNECT requests do not have a request body, the server may interpret the trailing body bytes as a subsequent pipelined HTTP/1.1 request on the connection, leaving the pooled connection desynchronized and causing the next caller that reuses it to read the response to the injected request. In reverse proxies (including httputil.ReverseProxy) that forward CONNECT requests through a shared Transport, this can lead to cross-user response poisoning.",
"evidence": "osv:DEBIAN-CVE-2026-56866",
"products": [
{
"name": {
"value": "golang-1.19",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.19.10-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.10-2",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.11-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.12-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.12-2",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.12-2~bpo11+1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.12-2~bpo12+1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.13-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.13-1~bpo11+1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.13-1~bpo12+1",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.8-2",
"evidence": "/affected/0/versions"
},
{
"value": "1.19.9-1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "golang-1.24",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.24.12-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.13-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.13-2",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.4-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.4-2",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.4-3",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.4-4",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.7-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.8-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.24.9-1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "golang-1.26",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.26.9-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": [
{
"value": "1.26.0-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.1-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.2-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.2-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.2-3",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.3-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.3-1~bpo13+1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.3-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.3-2~bpo13+1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.4-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.4-1~bpo13+1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.5-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.5-1~bpo13+1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.6-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.6-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.7-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.7-1~bpo13+1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.8-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.8-1~bpo13+1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26.8-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.26~rc2-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26~rc3-1",
"evidence": "/affected/2/versions"
},
{
"value": "1.26~rc3-2",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "golang-1.27",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.27.2-1",
"evidence": "/affected/3/ranges"
}
],
"affected_versions": [
{
"value": "1.27.0-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.27.0-1~bpo13+1",
"evidence": "/affected/3/versions"
},
{
"value": "1.27.1-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.27.1-2",
"evidence": "/affected/3/versions"
},
{
"value": "1.27.1-2~bpo13+1",
"evidence": "/affected/3/versions"
},
{
"value": "1.27~rc1-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.27~rc2-1",
"evidence": "/affected/3/versions"
},
{
"value": "1.27~rc3-1",
"evidence": "/affected/3/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "DEBIAN-CVE-2026-56866",
"aliases": [
"DEBIAN-CVE-2026-56866"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "golang-1.19",
"purl": "pkg:deb/debian/golang-1.19?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"1.19.10-1",
"1.19.10-2",
"1.19.11-1",
"1.19.12-1",
"1.19.12-2",
"1.19.12-2~bpo11+1",
"1.19.12-2~bpo12+1",
"1.19.13-1",
"1.19.13-1~bpo11+1",
"1.19.13-1~bpo12+1",
"1.19.8-2",
"1.19.9-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-56866.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "golang-1.24",
"purl": "pkg:deb/debian/golang-1.24?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"versions": [
"1.24.12-1",
"1.24.13-1",
"1.24.13-2",
"1.24.4-1",
"1.24.4-2",
"1.24.4-3",
"1.24.4-4",
"1.24.7-1",
"1.24.8-1",
"1.24.9-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-56866.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.26.9-1"
}
]
}
],
"package": {
"name": "golang-1.26",
"purl": "pkg:deb/debian/golang-1.26?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"1.26.0-1",
"1.26.1-1",
"1.26.2-1",
"1.26.2-2",
"1.26.2-3",
"1.26.3-1",
"1.26.3-1~bpo13+1",
"1.26.3-2",
"1.26.3-2~bpo13+1",
"1.26.4-1",
"1.26.4-1~bpo13+1",
"1.26.5-1",
"1.26.5-1~bpo13+1",
"1.26.6-1",
"1.26.6-2",
"1.26.7-1",
"1.26.7-1~bpo13+1",
"1.26.8-1",
"1.26.8-1~bpo13+1",
"1.26.8-2",
"1.26~rc2-1",
"1.26~rc3-1",
"1.26~rc3-2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-56866.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.27.2-1"
}
]
}
],
"package": {
"name": "golang-1.27",
"purl": "pkg:deb/debian/golang-1.27?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"versions": [
"1.27.0-1",
"1.27.0-1~bpo13+1",
"1.27.1-1",
"1.27.1-2",
"1.27.1-2~bpo13+1",
"1.27~rc1-1",
"1.27~rc2-1",
"1.27~rc3-1"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-56866.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-12T11:00:12.603390018Z",
"provider": "osv",
"upstream": [
"CVE-2026-56866"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2026-56866"
]
},
"related_cves": [
{
"value": "CVE-2026-56866",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 299760,
"published_at": "2026-10-08T23:17:01.62+00:00"
}