An ftp:// transfer configured with CURLUSESSL_NONE can reuse a pooled FTP
control connection that a previous easy handle upgraded with STARTTLS and
authenticated using a client certificate. The second handle performs neither a
new TLS handshake nor a new FTP login, so the server continues to authorize it
under the first handle's certificate identity.
{
"CWE": {
"desc": "Exposure of Data Element to Wrong Session",
"id": "CWE-488"
},
"URL": "https://curl.se/docs/CVE-2026-86411.json",
"affects": "both",
"issue": "https://hackerone.com/reports/3973190",
"last_affected": "8.21.0",
"package": "curl",
"severity": "Low",
"www": "https://curl.se/docs/CVE-2026-86411.html"
}"https://curl.se/docs/CURL-CVE-2026-86411.json"
[
{
"deprecated": false,
"digest": {
"function_hash": "137408457246507356568929899392562883991",
"length": 447
},
"id": "CURL-CVE-2026-86411-15332d56",
"signature_type": "Function",
"signature_version": "v1",
"source": "https://github.com/curl/curl.git/commit/72352daba01ba8072b6c1c0254cb77860ed1ab06",
"target": {
"file": "lib/url.c",
"function": "url_match_ssl_use"
}
},
{
"deprecated": false,
"digest": {
"line_hashes": [
"70148836786215020066010817017207029492",
"214623997824184722186061516736204732779",
"292579498451215313658478325050399342438",
"316184936108029474586670763707240004974"
],
"threshold": 0.9
},
"id": "CURL-CVE-2026-86411-1978bf57",
"signature_type": "Line",
"signature_version": "v1",
"source": "https://github.com/curl/curl.git/commit/72352daba01ba8072b6c1c0254cb77860ed1ab06",
"target": {
"file": "lib/url.c"
}
}
]
"2026-10-14T19:02:55Z"