Low
leaking host credentials to HTTP proxy
Type: advisorySources: OSV
An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2026-86414
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:38 UTC · Revision 1
Source evidence
An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.
osv:CURL-CVE-2026-86414
Complete source record
{
"id": "841e21e9eaf2ecc232ce29520d99d54eb609cfb7b1467d550be69d7c4ae9ed04",
"url": "https://osv.dev/vulnerability/CURL-CVE-2026-86414",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "leaking host credentials to HTTP proxy",
"summary": "An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.",
"evidence": "osv:CURL-CVE-2026-86414",
"products": [],
"severity": "low",
"structured": {
"id": "CURL-CVE-2026-86414",
"aliases": [
"CURL-CVE-2026-86414",
"CVE-2026-86414"
],
"affected": [
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "7.10.8"
},
{
"fixed": "8.14.3"
},
{
"introduced": "8.15.0"
},
{
"fixed": "8.16.2"
},
{
"introduced": "8.17.0"
},
{
"fixed": "8.20.2"
},
{
"introduced": "8.21.0"
},
{
"fixed": "8.23.0"
}
]
},
{
"repo": "https://github.com/curl/curl.git",
"type": "GIT",
"events": [
{
"introduced": "52ceab5e41a01b4d1227876d51a3680a3ce5a841"
},
{
"fixed": "2956af6c7451029fb12c12f8166dff211f930d52"
}
]
}
],
"versions": [
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"8.21.0",
"8.20.0",
"8.19.0",
"8.18.0",
"8.17.0",
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"curl-8_1_1",
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"curl-7_88_1",
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"curl-7_86_0",
"curl-7_85_0",
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"curl-7_83_0",
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"curl-7_79_1",
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"curl-7_66_0",
"curl-7_65_3",
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"curl-7_65_0",
"curl-7_64_1",
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"curl-7_54_0",
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"curl-7_22_0",
"curl-7_21_7",
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"curl-7_21_4",
"curl-7_21_3",
"curl-7_21_2",
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"curl-7_19_7",
"curl-7_19_6",
"curl-7_19_5",
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"curl-7_18_1",
"curl-7_18_0",
"curl-7_17_1",
"curl-7_17_0",
"curl-7_17_0-preldapfix",
"curl-7_16_4",
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],
"database_specific": {
"source": "https://curl.se/docs/CURL-CVE-2026-86414.json",
"vanir_signatures": [
{
"id": "CURL-CVE-2026-86414-7cce8e09",
"digest": {
"length": 2081,
"function_hash": "257637578855016841248657910277963897518"
},
"source": "https://github.com/curl/curl.git/commit/2956af6c7451029fb12c12f8166dff211f930d52",
"target": {
"file": "lib/cf-h1-proxy.c",
"function": "on_resp_header"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
},
{
"id": "CURL-CVE-2026-86414-a17b75a6",
"digest": {
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"target": {
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},
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"signature_type": "Line",
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{
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"digest": {
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"source": "https://github.com/curl/curl.git/commit/2956af6c7451029fb12c12f8166dff211f930d52",
"target": {
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"function": "Curl_http_proxy_inspect_tunnel_response"
},
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{
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"digest": {
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"source": "https://github.com/curl/curl.git/commit/2956af6c7451029fb12c12f8166dff211f930d52",
"target": {
"file": "lib/cf-h1-proxy.c"
},
"deprecated": false,
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{
"id": "CURL-CVE-2026-86414-faabc579",
"digest": {
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"source": "https://github.com/curl/curl.git/commit/2956af6c7451029fb12c12f8166dff211f930d52",
"target": {
"file": "lib/cf-h1-proxy.c",
"function": "on_resp_header_udp"
},
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"signature_type": "Function",
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}
],
"vanir_signatures_modified": "2026-10-25T01:05:13Z"
}
}
],
"modified": "2026-10-25T01:05:13.781523214Z",
"provider": "osv",
"references": [],
"provider_metadata": {
"CWE": {
"id": "CWE-201",
"desc": "Information Exposure Through Sent Data"
},
"URL": "https://curl.se/docs/CVE-2026-86414.json",
"www": "https://curl.se/docs/CVE-2026-86414.html",
"issue": "https://hackerone.com/reports/3993566",
"affects": "both",
"package": "curl",
"severity": "Low",
"last_affected": "8.22.0"
}
},
"related_cves": [
{
"value": "CVE-2026-86414",
"evidence": "/aliases"
}
],
"security_relevant": true,
"severity_evidence": "/database_specific/severity"
},
"source_id": "core-osv",
"document_id": 444360,
"published_at": "2026-10-14T08:00:00+00:00"
}