MSRC_CVE-2023-40217
Vulnerability from csaf_microsoft - Published: 2023-08-01 00:00 - Updated: 2023-10-11 00:00Summary
An issue was discovered in Python before 3.8.18 3.9.x before 3.9.18 3.10.x before 3.10.13 and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created receives data into the socket buffer and then is closed quickly there is a brief window where the SSLSocket instance will detect the socket as "not connected" and won't initiate a handshake but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.)
Notes
Additional Resources
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
Disclaimer
The information provided in the Microsoft Knowledge Base is provided \"as is\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
{
"document": {
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"text": "Public",
"tlp": {
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"notes": [
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"category": "general",
"text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
"title": "Additional Resources"
},
{
"category": "legal_disclaimer",
"text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
"title": "Disclaimer"
}
],
"publisher": {
"category": "vendor",
"contact_details": "secure@microsoft.com",
"name": "Microsoft Security Response Center",
"namespace": "https://msrc.microsoft.com"
},
"references": [
{
"category": "self",
"summary": "CVE-2023-40217 An issue was discovered in Python before 3.8.18 3.9.x before 3.9.18 3.10.x before 3.10.13 and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created receives data into the socket buffer and then is closed quickly there is a brief window where the SSLSocket instance will detect the socket as \"not connected\" and won\u0027t initiate a handshake but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.) - VEX",
"url": "https://msrc.microsoft.com/csaf/vex/2023/msrc_cve-2023-40217.json"
},
{
"category": "external",
"summary": "Microsoft Support Lifecycle",
"url": "https://support.microsoft.com/lifecycle"
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{
"category": "external",
"summary": "Common Vulnerability Scoring System",
"url": "https://www.first.org/cvss"
}
],
"title": "An issue was discovered in Python before 3.8.18 3.9.x before 3.9.18 3.10.x before 3.10.13 and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created receives data into the socket buffer and then is closed quickly there is a brief window where the SSLSocket instance will detect the socket as \"not connected\" and won\u0027t initiate a handshake but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.)",
"tracking": {
"current_release_date": "2023-10-11T00:00:00.000Z",
"generator": {
"date": "2025-10-20T00:37:53.023Z",
"engine": {
"name": "MSRC Generator",
"version": "1.0"
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},
"id": "msrc_CVE-2023-40217",
"initial_release_date": "2023-08-01T00:00:00.000Z",
"revision_history": [
{
"date": "2023-10-11T00:00:00.000Z",
"legacy_version": "1",
"number": "1",
"summary": "Information published."
}
],
"status": "final",
"version": "1"
}
},
"product_tree": {
"branches": [
{
"branches": [
{
"branches": [
{
"category": "product_version",
"name": "2.0",
"product": {
"name": "CBL Mariner 2.0",
"product_id": "17086"
}
}
],
"category": "product_name",
"name": "Azure Linux"
},
{
"branches": [
{
"category": "product_version_range",
"name": "\u003ccbl2 python3 3.9.19-1",
"product": {
"name": "\u003ccbl2 python3 3.9.19-1",
"product_id": "1"
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},
{
"category": "product_version",
"name": "cbl2 python3 3.9.19-1",
"product": {
"name": "cbl2 python3 3.9.19-1",
"product_id": "17386"
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],
"category": "product_name",
"name": "python3"
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"category": "vendor",
"name": "Microsoft"
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"relationships": [
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"full_product_name": {
"name": "\u003ccbl2 python3 3.9.19-1 as a component of CBL Mariner 2.0",
"product_id": "17086-1"
},
"product_reference": "1",
"relates_to_product_reference": "17086"
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{
"category": "default_component_of",
"full_product_name": {
"name": "cbl2 python3 3.9.19-1 as a component of CBL Mariner 2.0",
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},
"vulnerabilities": [
{
"cve": "CVE-2023-40217",
"notes": [
{
"category": "general",
"text": "mitre",
"title": "Assigning CNA"
}
],
"product_status": {
"fixed": [
"17386-17086"
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"known_affected": [
"17086-1"
]
},
"references": [
{
"category": "self",
"summary": "CVE-2023-40217 An issue was discovered in Python before 3.8.18 3.9.x before 3.9.18 3.10.x before 3.10.13 and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created receives data into the socket buffer and then is closed quickly there is a brief window where the SSLSocket instance will detect the socket as \"not connected\" and won\u0027t initiate a handshake but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.) - VEX",
"url": "https://msrc.microsoft.com/csaf/vex/2023/msrc_cve-2023-40217.json"
}
],
"remediations": [
{
"category": "vendor_fix",
"date": "2023-10-11T00:00:00.000Z",
"details": "3.9.19-1:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
"product_ids": [
"17086-1"
],
"url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
}
],
"scores": [
{
"cvss_v3": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 5.3,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"environmentalsScore": 0.0,
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"temporalScore": 5.3,
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"version": "3.1"
},
"products": [
"17086-1"
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}
],
"title": "An issue was discovered in Python before 3.8.18 3.9.x before 3.9.18 3.10.x before 3.10.13 and 3.11.x before 3.11.5. It primarily affects servers (such as HTTP servers) that use TLS client authentication. If a TLS server-side socket is created receives data into the socket buffer and then is closed quickly there is a brief window where the SSLSocket instance will detect the socket as \"not connected\" and won\u0027t initiate a handshake but buffered data will still be readable from the socket buffer. This data will not be authenticated if the server-side TLS peer is expecting client certificate authentication and is indistinguishable from valid TLS stream data. Data is limited in size to the amount that will fit in the buffer. (The TLS connection cannot directly be used for data exfiltration because the vulnerable code path requires that the connection be closed on initialization of the SSLSocket.)"
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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