curl — security advisory
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CURLOPT_USE_SSL were not included in the configuration match checks, causing them to match too easily. This could lead to libcurl using the wrong credentials when performing a transfer, potentially allowing unauthorized access to sensitive information.
- Products
- curl
- Affected versions
- Not specified
- Fixed versions
- 7.88.1-7
- CVEs
- CVE-2023-27535
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 09:55 UTC · Revision 1
Source evidence
An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CURLOPT_USE_SSL were not included in the configuration match checks, causing them to match too easily. This could lead to libcurl using the wrong credentials when performing a transfer, potentially allowing unauthorized access to sensitive information.
osv:DEBIAN-CVE-2023-27535
curl
Fixed versions: 7.88.1-7
curl
Fixed versions: 7.88.1-7
curl
Fixed versions: 7.88.1-7
Complete source record
{
"id": "a1253c531e9d96456e0bedf58d8e94dee19bd45a8f438cd3553c0a02b591c050",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2023-27535",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2023-27535",
"summary": "An authentication bypass vulnerability exists in libcurl <8.0.0 in the FTP connection reuse feature that can result in wrong credentials being used during subsequent transfers. Previously created connections are kept in a connection pool for reuse if they match the current setup. However, certain FTP settings such as CURLOPT_FTP_ACCOUNT, CURLOPT_FTP_ALTERNATIVE_TO_USER, CURLOPT_FTP_SSL_CCC, and CURLOPT_USE_SSL were not included in the configuration match checks, causing them to match too easily. This could lead to libcurl using the wrong credentials when performing a transfer, potentially allowing unauthorized access to sensitive information.",
"evidence": "osv:DEBIAN-CVE-2023-27535",
"products": [
{
"name": {
"value": "curl",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
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"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
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"severity": "medium",
"structured": {
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"aliases": [
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"metrics": [
{
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"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"
}
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"affected": [
{
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"package": {
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"purl": "pkg:deb/debian/curl?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
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},
"ecosystem_specific": {
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{
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"package": {
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"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-27535.json"
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{
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"package": {
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},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-27535.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-25T09:47:36.540354937Z",
"provider": "osv",
"upstream": [
"CVE-2023-27535"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2023-27535"
]
},
"related_cves": [
{
"value": "CVE-2023-27535",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 445307,
"published_at": "2023-03-30T20:15:07.483+00:00"
}