CVE-2026-23666

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{"bugzilla": {"description": "dotnet: .NET Framework: Denial of Service via Race Condition", "id": "2458271", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2458271"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-366", "details": ["A flaw was found in .NET Framework. An unauthorized attacker can exploit a race condition, which is a concurrent execution using shared resources with improper synchronization, to deny service over a network. This vulnerability can lead to a Denial of Service (DoS) for affected systems."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}, "name": "CVE-2026-23666", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "dotnet10.0", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "dotnet8.0", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "dotnet9.0", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "dotnet10.0", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "dotnet8.0", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "dotnet9.0", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "dotnet10.0", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "dotnet8.0", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "dotnet9.0", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-04-14T16:57:53Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-23666\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23666\nhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-23666"], "statement": "Important: A race condition in .NET Framework can lead to a Denial of Service. This flaw allows an unauthenticated attacker to exploit improper synchronization when using shared resources, causing affected systems to become unavailable. This impacts Red Hat Enterprise Linux 8, 9, and 10, as well as Fedora, where .NET is deployed.", "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,*]"}}], "enrichment": {"confidence": 95.0, "confidence_source": "inferred", "scores": [{"score": 95.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "product": ".net", "vendor": "microsoft"}, {"configurations": [{"platform": ["windows_server_2012", "windows_server_2012_(server_core_installation)", "windows_server_2012_r2", "windows_server_2012_r2_(server_core_installation)"], "status": "affected", "versions": {"scheme": "generic", "value": "[3.5.0,2.0.50727.8982)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "Microsoft .NET Framework 3.5", "source": "cna", "vendor": "Microsoft"}, "product": ".net_framework", "vendor": "microsoft"}, {"configurations": [{"platform": ["windows_10_version_1809_for_32-bit_systems", "windows_10_version_1809_for_arm64-based_systems", "windows_10_version_1809_for_x64-based_systems"], "status": "affected", "versions": {"scheme": "generic", "value": "[4.7.0,2.0.50727.9068)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "Microsoft .NET Framework 3.5 AND 4.7.2", "source": "cna", "vendor": "Microsoft"}, "product": ".net_framework", "vendor": "microsoft"}, {"configurations": [{"platform": ["windows_10_version_1809_for_32-bit_systems", "windows_10_version_1809_for_arm64-based_systems", "windows_10_version_1809_for_x64-based_systems", "windows_10_version_21h2_for_32-bit_systems", "windows_10_version_21h2_for_arm64-based_systems", "windows_10_version_21h2_for_x64-based_systems", "windows_10_version_22h2_for_32-bit_systems", "windows_10_version_22h2_for_arm64-based_systems", "windows_10_version_22h2_for_x64-based_systems", "windows_server_2022", "windows_server_2022_(server_core_installation)"], "status": "affected", "versions": {"scheme": "generic", "value": "[4.8.0,2.0.50727.9068)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "Microsoft .NET Framework 3.5 AND 4.8", "source": "cna", "vendor": "Microsoft"}, "product": ".net_framework", "vendor": "microsoft"}, {"configurations": [{"platform": ["windows_10_version_21h2_for_32-bit_systems", "windows_10_version_21h2_for_arm64-based_systems", "windows_10_version_21h2_for_x64-based_systems", "windows_10_version_22h2_for_32-bit_systems", "windows_10_version_22h2_for_arm64-based_systems", "windows_10_version_22h2_for_x64-based_systems", "windows_11_version_22h2_for_arm64-based_systems", "windows_11_version_22h2_for_x64-based_systems", "windows_11_version_23h2_for_arm64-based_systems", "windows_11_version_23h2_for_x64-based_systems", "windows_11_version_24h2_for_arm64-based_systems", "windows_11_version_24h2_for_x64-based_systems", "windows_11_version_25h2_for_arm_systems", "windows_11_version_25h2_for_x64-based_systems", "windows_11_version_26h1_for_arm64-based_systems", "windows_11_version_26h1_for_x64-based_systems", "windows_server_2022", "windows_server_2022_(server_core_installation)", "windows_server_2022,_23h2_edition_(server_core_installation)", "windows_server_2025", "windows_server_2025_(server_core_installation)"], "status": "affected", "versions": {"scheme": "generic", "value": "[4.8.1,2.0.50727.9181)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "Microsoft .NET Framework 3.5 AND 4.8.1", "source": "cna", "vendor": "Microsoft"}, "product": ".net_framework", "vendor": "microsoft"}, {"configurations": [{"platform": ["windows_server_2012", "windows_server_2012_(server_core_installation)", "windows_server_2012_r2", "windows_server_2012_r2_(server_core_installation)"], "status": "affected", "versions": {"scheme": "generic", "value": "[4.7.0,4.8.4801.0)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "Microsoft .NET Framework 4.6.2/4.7/4.7.1/4.7.2", "source": "cna", "vendor": "Microsoft"}, "product": ".net_framework", "vendor": "microsoft"}, {"configurations": [{"platform": ["windows_10_version_1607_for_32-bit_systems", "windows_10_version_1607_for_x64-based_systems", "windows_server_2012", "windows_server_2012_(server_core_installation)", "windows_server_2012_r2", "windows_server_2012_r2_(server_core_installation)"], "status": "affected", "versions": {"scheme": "generic", "value": "[4.8.0,4.8.4801.0)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "manual", "scores": [{"score": 100.0, "source": "manual"}]}, "original": {"product": "Microsoft .NET Framework 4.8", "source": "cna", "vendor": "Microsoft"}, "product": ".net_framework", "vendor": "microsoft"}], "analysis": {"en": {"generated_at": "2026-04-16T02:34:30.286545+00:00", "value": {"mitigation_remediation": ["Apply the latest security update for the .NET Framework from Microsoft\u2019s update guide", "If the patch cannot be applied immediately, restrict network access to the vulnerable components to prevent exploitation until the update is installed", "Monitor system logs and application performance for signs of service hangs or high CPU usage that could indicate exploitation attempts"], "summary": {"action": "Immediate Patch", "impact": "Denial of Service"}, "threat_synthesis": {"affected_systems": "The flaw affects multiple Microsoft .NET Framework releases, including versions 3.5, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, and 4.8.1. Any system that hosts applications built on these framework versions could be impacted, especially where network exposure is possible.", "description_and_impact": "Improper input validation in the .NET Framework enables an unauthorized attacker to trigger a denial of service over a network. This flaw can cause application processes to terminate or become unresponsive, resulting in loss of availability and potential interruption to user tasks. The issue is mapped to CWE-366 (Race Condition) and CWE-755 (Unsafe or Insecure Synchronization Mechanism), reflecting the underlying synchronization weaknesses that surface during input handling.)", "risk_and_exploitability": "The CVSS score of 7.5 indicates a high severity. The EPSS score is <1%, indicating a very low but non\u2011zero exploitation probability. The attack vector is inferred to be network\u2011based, as the description references denial of service over a network. The vulnerability is not listed in the CISA KEV catalog yet, but the high CVSS and potential for remote exploitation warrant prompt remediation."}}}}, "created": "2026-04-15T14:54:09.395370+00:00", "updated": "2026-04-16T02:45:06.079861+00:00", "vendors": ["microsoft", "microsoft$PRODUCT$.net", "microsoft$PRODUCT$.net_framework"]}