Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python's re.match() to check incoming origins against the allow_origin_pat configuration value. Because re.match() only anchors at the start of the string and does not require a full match, a pattern intended to match only a trusted domain (e.g., trusted.example.com) will also match any origin that begins with that domain followed by additional characters (e.g., trusted.example.com.evil.com). An attacker who controls such a domain can bypass the CORS origin restriction and make cross-origin requests to the Jupyter Server API from an untrusted site. This issue has been fixed in version 2.18.0.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-777"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40110.json",
"unresolved_ranges": [
{
"extracted_events": [
{
"range": [
{
"last_affected": "2.17.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StringRangeExpression"
}
]
},
{
"extracted_events": [
{
"range": [
{
"fixed": "2.18.0"
},
{
"last_affected": "2.17.0"
}
],
"source": "DESCRIPTION"
}
]
}
]
}{
"extracted_events": [
{
"range": [
{
"fixed": "057869a327c46730afede3eab0ca2d2e3e74acea"
}
],
"source": "REFERENCES_COMMIT"
},
{
"range": [
{
"fixed": "49b34392feaa97735b3b777e3baf8f22f2a14ed8"
}
],
"source": "REFERENCES_COMMIT"
}
]
}