{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-19553", "assignerOrgId": "28c92f92-d60d-412d-b760-e73465c3df22", "state": "PUBLISHED", "assignerShortName": "PSF", "dateReserved": "2026-08-11T15:22:03.833Z", "datePublished": "2026-09-30T16:17:39.368Z", "dateUpdated": "2026-10-16T18:33:12.475Z"}, "containers": {"cna": {"affected": [{"defaultStatus": "unaffected", "modules": ["ssl"], "product": "CPython", "repo": "https://github.com/python/cpython", "vendor": "Python Software Foundation", "versions": [{"version": "0", "lessThan": "3.10.22", "status": "affected", "versionType": "python"}, {"version": "3.11.0", "lessThan": "3.11.17", "status": "affected", "versionType": "python"}, {"version": "3.12.0", "lessThan": "3.12.15", "status": "affected", "versionType": "python"}, {"version": "3.13.0", "lessThan": "3.13.16", "status": "affected", "versionType": "python"}, {"version": "3.14.0", "lessThan": "3.14.8", "status": "affected", "versionType": "python"}, {"version": "3.15.0a1", "lessThan": "3.15.0rc3", "status": "affected", "versionType": "python"}]}], "credits": [{"lang": "en", "type": "reporter", "value": "devdanzin (https://github.com/devdanzin)"}, {"lang": "en", "type": "analyst", "value": "Bhuvansh (https://github.com/BHUVANSH855)"}, {"lang": "en", "type": "remediation reviewer", "value": "B\u00e9n\u00e9dikt Tran (https://github.com/picnixz)"}, {"lang": "en", "type": "coordinator", "value": "Seth Larson (https://github.com/sethmlarson)"}], "descriptions": [{"lang": "en", "supportingMedia": [{"type": "text/html", "value": "<p><code>ssl.SSLContext.wrap_bio()</code> didn't require the <code>server_hostname</code> argument\nto not be <code>None</code> if <code>ssl.SSLContext.check_hostname</code> was set. Due to a\nmissing parameter check in <code>SSLObject</code>, if the <code>server_hostname</code> argument\nisn't supplied then hostname verification would be silently skipped.</p>\n<p>This defect could lead to programs where certificate hostname verification\n<em>*appeared*</em> to be succeeding with <code>SSLContext.check_hostname = True</code> and no\n<code>ValueError</code> being raised due to misconfiguration.</p>\n<p>If the program passes a <code>server_hostname</code> value that isn't an empty string\nor <code>None</code> to any of these APIs then certificate hostname verification\nproceeds as expected and the program is not affected by this vulnerability.</p>\n<p>Mitigating this vulnerability doesn't require updating Python or applying\nthe patch. To mitigate, pass a valid non-<code>None</code> and non-empty\n<code>server_hostname</code> value to <code>SSLContext.wrap_bio()</code>,\n<code>asyncio.create_connection()</code>, or <code>asyncio.loop.start_tls()</code> and\ncertificate hostname verification will proceed as expected. Upgrading to\nthe latest version of Python or applying the patch only changes the\nbehavior from silently skipping hostname verification to raising a\n<code>ValueError</code>, similar to <code>SSLContext.wrap_socket()</code>, when <code>server_hostname</code>\nisn't supplied.</p>"}], "value": "ssl.SSLContext.wrap_bio() didn't require the server_hostname argument\nto not be None if ssl.SSLContext.check_hostname was set. Due to a\nmissing parameter check in SSLObject, if the server_hostname argument\nisn't supplied then hostname verification would be silently skipped.\n\n\nThis defect could lead to programs where certificate hostname verification\n*appeared* to be succeeding with SSLContext.check_hostname = True and no\nValueError being raised due to misconfiguration.\n\n\nIf the program passes a server_hostname value that isn't an empty string\nor None to any of these APIs then certificate hostname verification\nproceeds as expected and the program is not affected by this vulnerability.\n\n\nMitigating this vulnerability doesn't require updating Python or applying\nthe patch. To mitigate, pass a valid non-None and non-empty\nserver_hostname value to SSLContext.wrap_bio(),\nasyncio.create_connection(), or asyncio.loop.start_tls() and\ncertificate hostname verification will proceed as expected. Upgrading to\nthe latest version of Python or applying the patch only changes the\nbehavior from silently skipping hostname verification to raising a\nValueError, similar to SSLContext.wrap_socket(), when server_hostname\nisn't supplied."}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 7.6, "baseSeverity": "HIGH", "exploitMaturity": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-297", "description": "CWE-297", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "28c92f92-d60d-412d-b760-e73465c3df22", "shortName": "PSF", "dateUpdated": "2026-10-03T00:36:35.156Z"}, "references": [{"tags": ["patch"], "url": "https://github.com/python/cpython/pull/158503"}, {"tags": ["issue-tracking"], "url": "https://github.com/python/cpython/issues/156793"}, {"tags": ["vendor-advisory"], "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/QNZRG3YOAMTHDCMVCICXGY6YEFPY2VDL/"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/1697ea386c707142555d98a1263176bbbc014a96"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/641390146a16a38e6701923f4ee4f1940ae77082"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/966bf426d0b6c31c1b0a255ff14a17143a466ced"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/f4e43ba525187282f2011da0e6ffc0d2b08d8062"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/869069d52ce0efab2f8c38197e92cdaaa312f1ed"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/5867d4e4ae6d1062352baf6b497a4026e8578ccf"}, {"tags": ["patch"], "url": "https://github.com/python/cpython/commit/bdebbf9b366ec91e9cd9daa0b3510c9e84b60b80"}], "source": {"discovery": "UNKNOWN"}, "title": "SSLContext.wrap_bio() missing validation of server_hostname parameter", "x_generator": {"engine": "cvelib 1.8.0"}}, "adp": [{"title": "CVE Program Container", "references": [{"url": "http://www.openwall.com/lists/oss-security/2026/09/30/16"}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2026-09-30T18:09:40.939Z"}}, {"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-10-16T18:33:08.291056Z", "id": "CVE-2026-19553", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T18:33:12.475Z"}}]}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "modules": ["ssl"], "product": "CPython", "repo": "https://github.com/python/cpython", "vendor": "Python Software Foundation", "versions": [{"lessThan": "3.10.22", "status": "affected", "version": "0", "versionType": "python"}, {"lessThan": "3.11.17", "status": "affected", "version": "3.11.0", "versionType": "python"}, {"lessThan": "3.12.15", "status": "affected", "version": "3.12.0", "versionType": "python"}, {"lessThan": "3.13.16", "status": "affected", "version": "3.13.0", "versionType": "python"}, {"lessThan": "3.14.8", "status": "affected", "version": "3.14.0", "versionType": "python"}, {"lessThan": "3.15.0rc3", "status": "affected", "version": "3.15.0a1", "versionType": "python"}]}], "source": "cna@python.org"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "ssl.SSLContext.wrap_bio() didn't require the server_hostname argument\nto not be None if ssl.SSLContext.check_hostname was set. Due to a\nmissing parameter check in SSLObject, if the server_hostname argument\nisn't supplied then hostname verification would be silently skipped.\n\n\nThis defect could lead to programs where certificate hostname verification\n*appeared* to be succeeding with SSLContext.check_hostname = True and no\nValueError being raised due to misconfiguration.\n\n\nIf the program passes a server_hostname value that isn't an empty string\nor None to any of these APIs then certificate hostname verification\nproceeds as expected and the program is not affected by this vulnerability.\n\n\nMitigating this vulnerability doesn't require updating Python or applying\nthe patch. To mitigate, pass a valid non-None and non-empty\nserver_hostname value to SSLContext.wrap_bio(),\nasyncio.create_connection(), or asyncio.loop.start_tls() and\ncertificate hostname verification will proceed as expected. Upgrading to\nthe latest version of Python or applying the patch only changes the\nbehavior from silently skipping hostname verification to raising a\nValueError, similar to SSLContext.wrap_socket(), when server_hostname\nisn't supplied."}], "id": "CVE-2026-19553", "lastModified": "2026-10-16T19:17:06.673", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.6, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "cna@python.org", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-19553", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T18:33:08.291056Z", "version": "2.0.3"}}]}, "published": "2026-09-30T17:16:45.880", "references": [{"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/1697ea386c707142555d98a1263176bbbc014a96"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/5867d4e4ae6d1062352baf6b497a4026e8578ccf"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/641390146a16a38e6701923f4ee4f1940ae77082"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/869069d52ce0efab2f8c38197e92cdaaa312f1ed"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/966bf426d0b6c31c1b0a255ff14a17143a466ced"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/bdebbf9b366ec91e9cd9daa0b3510c9e84b60b80"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/commit/f4e43ba525187282f2011da0e6ffc0d2b08d8062"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/issues/156793"}, {"source": "cna@python.org", "url": "https://github.com/python/cpython/pull/158503"}, {"source": "cna@python.org", "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/QNZRG3YOAMTHDCMVCICXGY6YEFPY2VDL/"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "url": "http://www.openwall.com/lists/oss-security/2026/09/30/16"}], "sourceIdentifier": "cna@python.org", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-297"}], "source": "cna@python.org", "type": "Secondary"}]}

{"bugzilla": {"description": "python: python: Certificate verification bypass via missing server_hostname validation in SSLContext.wrap_bio()", "id": "2544127", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2544127"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N", "status": "draft"}, "cwe": "CWE-295", "details": ["A flaw was found in Python. When establishing secure connections using the SSLContext.wrap_bio() function with hostname checking enabled, the module fails to validate that a target server hostname is supplied. Because of this missing check, certificate hostname verification is silently skipped rather than triggering an error. A remote man-in-the-middle attacker could exploit this defect to spoof trusted endpoints and intercept or tamper with sensitive encrypted traffic."], "name": "CVE-2026-19553", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "python3.12", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "python3.14", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Affected", "package_name": "python", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "python", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Affected", "package_name": "python3", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "python3", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "python3.12", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "python36:3.6/python36", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "python3.12", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "python3.14", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "python3.9", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:enterprise_linux_ai:3", "fix_state": "Affected", "package_name": "rhelai3/bootc-aws-cuda-rhel9", "product_name": "Red Hat Enterprise Linux AI (RHEL AI) 3"}, {"cpe": "cpe:/a:redhat:enterprise_linux_ai:3", "fix_state": "Affected", "package_name": "rhelai3/bootc-azure-cuda-rhel9", "product_name": "Red Hat Enterprise Linux AI (RHEL AI) 3"}, {"cpe": "cpe:/a:redhat:enterprise_linux_ai:3", "fix_state": "Affected", "package_name": "rhelai3/bootc-azure-rocm-rhel9", "product_name": "Red Hat Enterprise Linux AI (RHEL AI) 3"}, {"cpe": "cpe:/a:redhat:enterprise_linux_ai:3", "fix_state": "Affected", "package_name": "rhelai3/bootc-cuda-rhel9", "product_name": "Red Hat Enterprise Linux AI (RHEL AI) 3"}, {"cpe": "cpe:/a:redhat:enterprise_linux_ai:3", "fix_state": "Affected", "package_name": "rhelai3/bootc-gaudi-rhel9", "product_name": "Red Hat Enterprise Linux AI (RHEL AI) 3"}, {"cpe": "cpe:/a:redhat:enterprise_linux_ai:3", "fix_state": "Affected", "package_name": "rhelai3/bootc-gcp-cuda-rhel9", "product_name": "Red Hat Enterprise Linux AI (RHEL AI) 3"}, {"cpe": "cpe:/a:redhat:enterprise_linux_ai:3", "fix_state": "Affected", "package_name": "rhelai3/bootc-rocm-rhel9", "product_name": "Red Hat Enterprise Linux AI (RHEL AI) 3"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "python3.10", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "python3.11", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "python3.12", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "python3.13", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:hummingbird:1", "fix_state": "Affected", "package_name": "python3.14", "product_name": "Red Hat Hardened Images"}, {"cpe": "cpe:/a:redhat:container_native_virtualization:4", "fix_state": "Affected", "package_name": "openshift-virtualization/ocp-virt-validation-checkup-rhel9", "product_name": "Red Hat OpenShift Virtualization 4"}, {"cpe": "cpe:/a:redhat:ansible_portal:2", "fix_state": "Affected", "package_name": "ansible-automation-platform/bootc-automation-portal-rhel9", "product_name": "Self-service automation portal 2"}], "public_date": "2026-09-30T16:17:39Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-19553\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-19553\nhttps://github.com/python/cpython/issues/156793\nhttps://github.com/python/cpython/pull/158503\nhttps://mail.python.org/archives/list/security-announce@python.org/thread/QNZRG3YOAMTHDCMVCICXGY6YEFPY2VDL/"], "threat_severity": "Important"}