Low
Automatic referer leaks credentials
Type: advisorySources: OSV
libcurl does not strip off user credentials from the URL when automatically populating the `Referer:` HTTP request header field in outgoing HTTP requests, and therefore risks leaking sensitive data to the server that is the target of the second HTTP request. libcurl automatically sets the `Referer:` HTTP request header field in outgoing HTTP requests if the `CURLOPT_AUTOREFERER` option is set. With the curl tool, it is enabled with `--referer ";auto"`.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2021-22876
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:38 UTC · Revision 1
Source evidence
libcurl does not strip off user credentials from the URL when automatically populating the `Referer:` HTTP request header field in outgoing HTTP requests, and therefore risks leaking sensitive data to the server that is the target of the second HTTP request. libcurl automatically sets the `Referer:` HTTP request header field in outgoing HTTP requests if the `CURLOPT_AUTOREFERER` option is set. With the curl tool, it is enabled with `--referer ";auto"`.
osv:CURL-CVE-2021-22876
Complete source record
{
"id": "18ae38097487a35ac455b72f668fc82294a869f259514c7a426869e198fc8a00",
"url": "https://osv.dev/vulnerability/CURL-CVE-2021-22876",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "Automatic referer leaks credentials",
"summary": "libcurl does not strip off user credentials from the URL when automatically populating the `Referer:` HTTP request header field in outgoing HTTP requests, and therefore risks leaking sensitive data to the server that is the target of the second HTTP request. libcurl automatically sets the `Referer:` HTTP request header field in outgoing HTTP requests if the `CURLOPT_AUTOREFERER` option is set. With the curl tool, it is enabled with `--referer \";auto\"`.",
"evidence": "osv:CURL-CVE-2021-22876",
"products": [],
"severity": "low",
"structured": {
"id": "CURL-CVE-2021-22876",
"aliases": [
"CURL-CVE-2021-22876",
"CVE-2021-22876"
],
"affected": [
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "7.1.1"
},
{
"fixed": "7.76.0"
}
]
},
{
"repo": "https://github.com/curl/curl.git",
"type": "GIT",
"events": [
{
"introduced": "f30ffef477636dc10a72eb30590a84a0218e5935"
},
{
"fixed": "7214288898f5625a6cc196e22a74232eada7861c"
}
]
}
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"database_specific": {
"source": "https://curl.se/docs/CURL-CVE-2021-22876.json",
"vanir_signatures": [
{
"id": "CURL-CVE-2021-22876-5478abb6",
"digest": {
"threshold": 0.9,
"line_hashes": [
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"240970743308685232172422878968984381962",
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]
},
"source": "https://github.com/curl/curl.git/commit/7214288898f5625a6cc196e22a74232eada7861c",
"target": {
"file": "lib/transfer.c"
},
"deprecated": false,
"signature_type": "Line",
"signature_version": "v1"
},
{
"id": "CURL-CVE-2021-22876-584f6dd4",
"digest": {
"length": 3402,
"function_hash": "22806353787620361724789102913607449117"
},
"source": "https://github.com/curl/curl.git/commit/7214288898f5625a6cc196e22a74232eada7861c",
"target": {
"file": "lib/transfer.c",
"function": "Curl_follow"
},
"deprecated": false,
"signature_type": "Function",
"signature_version": "v1"
}
],
"vanir_signatures_modified": "2026-10-25T01:05:06Z"
}
}
],
"modified": "2026-10-25T01:05:06.250344523Z",
"provider": "osv",
"references": [],
"provider_metadata": {
"CWE": {
"id": "CWE-359",
"desc": "Exposure of Private Personal Information to an Unauthorized Actor"
},
"URL": "https://curl.se/docs/CVE-2021-22876.json",
"www": "https://curl.se/docs/CVE-2021-22876.html",
"award": {
"amount": "800",
"currency": "USD"
},
"issue": "https://hackerone.com/reports/1101882",
"affects": "both",
"package": "curl",
"severity": "Low",
"last_affected": "7.75.0"
}
},
"related_cves": [
{
"value": "CVE-2021-22876",
"evidence": "/aliases"
}
],
"security_relevant": true,
"severity_evidence": "/database_specific/severity"
},
"source_id": "core-osv",
"document_id": 444332,
"published_at": "2021-03-31T08:00:00+00:00"
}