MSRC_CVE-2021-20194
Vulnerability from csaf_microsoft - Published: 2021-02-02 00:00 - Updated: 2021-12-16 00:00Summary
There is a vulnerability in the linux kernel versions higher than 5.2 (if kernel compiled with config params CONFIG_BPF_SYSCALL=y CONFIG_BPF=y CONFIG_CGROUPS=y CONFIG_CGROUP_BPF=y CONFIG_HARDENED_USERCOPY not set and BPF hook to getsockopt is registered). As result of BPF execution the local user can trigger bug in __cgroup_bpf_run_filter_getsockopt() function that can lead to heap overflow (because of non-hardened usercopy). The impact of attack could be deny of service or possibly privileges escalation.
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": {
"category": "csaf_vex",
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"text": "Public",
"tlp": {
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"notes": [
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"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"
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"references": [
{
"category": "self",
"summary": "CVE-2021-20194 There is a vulnerability in the linux kernel versions higher than 5.2 (if kernel compiled with config params CONFIG_BPF_SYSCALL=y CONFIG_BPF=y CONFIG_CGROUPS=y CONFIG_CGROUP_BPF=y CONFIG_HARDENED_USERCOPY not set and BPF hook to getsockopt is registered). As result of BPF execution the local user can trigger bug in __cgroup_bpf_run_filter_getsockopt() function that can lead to heap overflow (because of non-hardened usercopy). The impact of attack could be deny of service or possibly privileges escalation. - VEX",
"url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-20194.json"
},
{
"category": "external",
"summary": "Microsoft Support Lifecycle",
"url": "https://support.microsoft.com/lifecycle"
},
{
"category": "external",
"summary": "Common Vulnerability Scoring System",
"url": "https://www.first.org/cvss"
}
],
"title": "There is a vulnerability in the linux kernel versions higher than 5.2 (if kernel compiled with config params CONFIG_BPF_SYSCALL=y CONFIG_BPF=y CONFIG_CGROUPS=y CONFIG_CGROUP_BPF=y CONFIG_HARDENED_USERCOPY not set and BPF hook to getsockopt is registered). As result of BPF execution the local user can trigger bug in __cgroup_bpf_run_filter_getsockopt() function that can lead to heap overflow (because of non-hardened usercopy). The impact of attack could be deny of service or possibly privileges escalation.",
"tracking": {
"current_release_date": "2021-12-16T00:00:00.000Z",
"generator": {
"date": "2025-10-19T21:43:39.663Z",
"engine": {
"name": "MSRC Generator",
"version": "1.0"
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},
"id": "msrc_CVE-2021-20194",
"initial_release_date": "2021-02-02T00:00:00.000Z",
"revision_history": [
{
"date": "2021-02-27T00:00:00.000Z",
"legacy_version": "1",
"number": "1",
"summary": "Information published."
},
{
"date": "2021-12-16T00:00:00.000Z",
"legacy_version": "1.1",
"number": "2",
"summary": "Added kernel to CBL-Mariner 2.0"
}
],
"status": "final",
"version": "2"
}
},
"product_tree": {
"branches": [
{
"branches": [
{
"branches": [
{
"category": "product_version",
"name": "2.0",
"product": {
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"product_id": "17086"
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},
{
"category": "product_version",
"name": "3.0",
"product": {
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"product_id": "17084"
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],
"category": "product_name",
"name": "Azure Linux"
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{
"branches": [
{
"category": "product_version_range",
"name": "\u003ccbl2 kernel 5.15.26.1-1",
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"product_id": "2"
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{
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"name": "cbl2 kernel 5.15.26.1-1",
"product": {
"name": "cbl2 kernel 5.15.26.1-1",
"product_id": "18781"
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},
{
"category": "product_version_range",
"name": "\u003cazl3 kernel 6.6.35.1-4",
"product": {
"name": "\u003cazl3 kernel 6.6.35.1-4",
"product_id": "3"
}
},
{
"category": "product_version",
"name": "azl3 kernel 6.6.35.1-4",
"product": {
"name": "azl3 kernel 6.6.35.1-4",
"product_id": "17065"
}
},
{
"category": "product_version_range",
"name": "\u003cazl3 kernel 6.6.92.2-1",
"product": {
"name": "\u003cazl3 kernel 6.6.92.2-1",
"product_id": "1"
}
},
{
"category": "product_version",
"name": "azl3 kernel 6.6.92.2-1",
"product": {
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"product_id": "19529"
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}
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"category": "product_name",
"name": "kernel"
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],
"category": "vendor",
"name": "Microsoft"
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"relationships": [
{
"category": "default_component_of",
"full_product_name": {
"name": "\u003ccbl2 kernel 5.15.26.1-1 as a component of CBL Mariner 2.0",
"product_id": "17086-2"
},
"product_reference": "2",
"relates_to_product_reference": "17086"
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{
"category": "default_component_of",
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{
"category": "default_component_of",
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"name": "\u003cazl3 kernel 6.6.35.1-4 as a component of Azure Linux 3.0",
"product_id": "17084-3"
},
"product_reference": "3",
"relates_to_product_reference": "17084"
},
{
"category": "default_component_of",
"full_product_name": {
"name": "azl3 kernel 6.6.35.1-4 as a component of Azure Linux 3.0",
"product_id": "17065-17084"
},
"product_reference": "17065",
"relates_to_product_reference": "17084"
},
{
"category": "default_component_of",
"full_product_name": {
"name": "\u003cazl3 kernel 6.6.92.2-1 as a component of Azure Linux 3.0",
"product_id": "17084-1"
},
"product_reference": "1",
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},
{
"category": "default_component_of",
"full_product_name": {
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},
"vulnerabilities": [
{
"cve": "CVE-2021-20194",
"cwe": {
"id": "CWE-20",
"name": "Improper Input Validation"
},
"notes": [
{
"category": "general",
"text": "redhat",
"title": "Assigning CNA"
}
],
"product_status": {
"fixed": [
"18781-17086",
"17065-17084",
"19529-17084"
],
"known_affected": [
"17086-2",
"17084-3",
"17084-1"
]
},
"references": [
{
"category": "self",
"summary": "CVE-2021-20194 There is a vulnerability in the linux kernel versions higher than 5.2 (if kernel compiled with config params CONFIG_BPF_SYSCALL=y CONFIG_BPF=y CONFIG_CGROUPS=y CONFIG_CGROUP_BPF=y CONFIG_HARDENED_USERCOPY not set and BPF hook to getsockopt is registered). As result of BPF execution the local user can trigger bug in __cgroup_bpf_run_filter_getsockopt() function that can lead to heap overflow (because of non-hardened usercopy). The impact of attack could be deny of service or possibly privileges escalation. - VEX",
"url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-20194.json"
}
],
"remediations": [
{
"category": "vendor_fix",
"date": "2021-02-27T00:00:00.000Z",
"details": "5.15.26.1-1:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
"product_ids": [
"17086-2"
],
"url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
},
{
"category": "vendor_fix",
"date": "2021-02-27T00:00:00.000Z",
"details": "6.6.35.1-4:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
"product_ids": [
"17084-3",
"17084-1"
],
"url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
}
],
"scores": [
{
"cvss_v3": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"environmentalsScore": 0.0,
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"temporalScore": 7.8,
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"products": [
"17086-2",
"17084-3",
"17084-1"
]
}
],
"title": "There is a vulnerability in the linux kernel versions higher than 5.2 (if kernel compiled with config params CONFIG_BPF_SYSCALL=y CONFIG_BPF=y CONFIG_CGROUPS=y CONFIG_CGROUP_BPF=y CONFIG_HARDENED_USERCOPY not set and BPF hook to getsockopt is registered). As result of BPF execution the local user can trigger bug in __cgroup_bpf_run_filter_getsockopt() function that can lead to heap overflow (because of non-hardened usercopy). The impact of attack could be deny of service or possibly privileges escalation."
}
]
}
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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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