High
Security advisory
In Python 3.6 through 3.6.10, 3.7 through 3.7.8, 3.8 through 3.8.4rc1, and 3.9 through 3.9.0b4 on Windows, a Trojan horse python3.dll might be used in cases where CPython is embedded in a native application. This occurs because python3X.dll may use an invalid search path for python3.dll loading (after Py_SetPath has been used). NOTE: this issue CANNOT occur when using python.exe from a standard (non-embedded) Python installation on Windows.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2020-15523
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 10:53 UTC · Revision 1
Source evidence
In Python 3.6 through 3.6.10, 3.7 through 3.7.8, 3.8 through 3.8.4rc1, and 3.9 through 3.9.0b4 on Windows, a Trojan horse python3.dll might be used in cases where CPython is embedded in a native application. This occurs because python3X.dll may use an invalid search path for python3.dll loading (after Py_SetPath has been used). NOTE: this issue CANNOT occur when using python.exe from a standard (non-embedded) Python installation on Windows.
osv:CVE-2020-15523
Complete source record
{
"id": "d9644488a1d5fc03e978fc31e3f2541cda6d9954e7a4ff0538635261430e7518",
"url": "https://osv.dev/vulnerability/CVE-2020-15523",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "CVE-2020-15523",
"summary": "In Python 3.6 through 3.6.10, 3.7 through 3.7.8, 3.8 through 3.8.4rc1, and 3.9 through 3.9.0b4 on Windows, a Trojan horse python3.dll might be used in cases where CPython is embedded in a native application. This occurs because python3X.dll may use an invalid search path for python3.dll loading (after Py_SetPath has been used). NOTE: this issue CANNOT occur when using python.exe from a standard (non-embedded) Python installation on Windows.",
"evidence": "osv:CVE-2020-15523",
"products": [],
"severity": "high",
"structured": {
"id": "CVE-2020-15523",
"aliases": [
"BIT-libpython-2020-15523",
"BIT-python-2020-15523",
"BIT-python-min-2020-15523",
"CVE-2020-15523",
"PSF-2020-4"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
}
],
"affected": [
{
"ranges": [
{
"repo": "https://github.com/python/cpython",
"type": "GIT",
"events": [
{
"introduced": "2e789a1f1d84b343a996e8654590703b5fbdd441"
},
{
"fixed": "426b022776672fdf3d71ddd98d89af341c88080f"
},
{
"introduced": "5c4568a05a0a62b5947c55f68f9f2ecfb90a4f12"
},
{
"fixed": "c0a9afe2ac1820409e6173bd1893ebee2cf50270"
},
{
"introduced": "1bf9cc509326bc42cd8cb1650eb9bf64550d817e"
},
{
"fixed": "13c94747c74437e594b7fc242ff7da668e81887c"
},
{
"introduced": "fa919fdf2583bdfead1df00e842f24f30b2a34bf"
},
{
"fixed": "dfa645a65ec0788d98851130a217e029d1cc4e9b"
},
{
"introduced": "6c38841c08edd6b0727903ec3f1acd10dc9766f6"
},
{
"last_affected": "6c38841c08edd6b0727903ec3f1acd10dc9766f6"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:python:python:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "3.5.0"
},
{
"fixed": "3.5.10"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:python:python:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "3.6.0"
},
{
"fixed": "3.6.12"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:python:python:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "3.7.0"
},
{
"fixed": "3.7.9"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:python:python:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "3.8.0"
},
{
"fixed": "3.8.4"
}
],
"source": "CPE_RANGE"
},
{
"cpe": "cpe:2.3:a:python:python:3.8.4:rc1:*:*:*:*:*:*",
"range": [
{
"introduced": "3.8.4-rc1"
},
{
"last_affected": "3.8.4-rc1"
}
],
"source": "CPE_STRING"
}
]
}
}
],
"versions": [
"3.8.4-rc1",
"v3.8.4rc1"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-15523.json"
}
}
],
"modified": "2026-10-20T10:51:55.081716596Z",
"provider": "osv",
"references": [
"https://cert-portal.siemens.com/productcert/html/ssa-398330.html",
"https://bugs.python.org/issue29778",
"https://github.com/python/cpython/pull/21297",
"https://security.netapp.com/advisory/ntap-20210312-0004/"
],
"provider_metadata": {
"unresolved_ranges": [
{
"cpes": [
"cpe:2.3:a:python:python:3.9.0:alpha1:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:alpha2:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:alpha3:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:alpha4:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:alpha5:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:alpha6:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:beta1:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:beta2:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:beta3:*:*:*:*:*:*",
"cpe:2.3:a:python:python:3.9.0:beta4:*:*:*:*:*:*"
],
"vendor_product": "python:python",
"extracted_events": [
{
"range": [
{
"introduced": "3.9.0-alpha1"
},
{
"last_affected": "3.9.0-alpha1"
},
{
"introduced": "3.9.0-alpha2"
},
{
"last_affected": "3.9.0-alpha2"
},
{
"introduced": "3.9.0-alpha3"
},
{
"last_affected": "3.9.0-alpha3"
},
{
"introduced": "3.9.0-alpha4"
},
{
"last_affected": "3.9.0-alpha4"
},
{
"introduced": "3.9.0-alpha5"
},
{
"last_affected": "3.9.0-alpha5"
},
{
"introduced": "3.9.0-alpha6"
},
{
"last_affected": "3.9.0-alpha6"
},
{
"introduced": "3.9.0-beta1"
},
{
"last_affected": "3.9.0-beta1"
},
{
"introduced": "3.9.0-beta2"
},
{
"last_affected": "3.9.0-beta2"
},
{
"introduced": "3.9.0-beta3"
},
{
"last_affected": "3.9.0-beta3"
},
{
"introduced": "3.9.0-beta4"
},
{
"last_affected": "3.9.0-beta4"
}
],
"source": "CPE_STRING"
}
]
}
]
}
},
"related_cves": [
{
"value": "CVE-2020-15523",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 383128,
"published_at": "2020-07-04T23:15:10.313+00:00"
}