{"id":"CVE-2021-3737","state":"PUBLISHED","title":"A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client scri","description":"A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client script enter an infinite loop, consuming CPU time. The highest threat from this vulnerability is to system availability.","publishedAt":"2022-03-04T00:00:00.000Z","updatedAt":"2026-10-14T09:49:50.701Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"redhat","products":["n/a python"],"affected":[{"vendor":"n/a","product":"python","versions":[{"version":"Fixed in python v3.6.14, python v3.7.11, python v3.8.11, python v3.9.6, python v3.10.0b2","status":"affected"}]}],"references":["https://bugs.python.org/issue44022","https://github.com/python/cpython/pull/25916","https://bugzilla.redhat.com/show_bug.cgi?id=1995162","https://github.com/python/cpython/pull/26503","https://ubuntu.com/security/CVE-2021-3737","https://www.oracle.com/security-alerts/cpujul2022.html","https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html","https://security.netapp.com/advisory/ntap-20220407-0009/","https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html","https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html","https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html","https://lists.debian.org/debian-lts-announce/2024/11/msg00024.html","https://cert-portal.siemens.com/productcert/html/ssa-398330.html"],"weaknesses":["CWE-835"],"ingestedAt":"2026-10-29T19:48:55.807Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/3xxx/CVE-2021-3737.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-3737","state":"PUBLISHED","datePublished":"2022-03-04T00:00:00.000Z","dateUpdated":"2026-10-14T09:49:50.701Z","assignerShortName":"redhat","assignerOrgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateReserved":"2021-08-26T00:00:00.000Z"},"containers":{"cna":{"descriptions":[{"lang":"en","value":"A flaw was found in python. An improperly handled HTTP response in the HTTP client code of python may allow a remote attacker, who controls the HTTP server, to make the client script enter an infinite loop, consuming CPU time. The highest threat from this vulnerability is to system availability."}],"affected":[{"vendor":"n/a","product":"python","versions":[{"version":"Fixed in python v3.6.14, python v3.7.11, python v3.8.11, python v3.9.6, python v3.10.0b2","status":"affected"}]}],"references":[{"url":"https://bugs.python.org/issue44022"},{"url":"https://github.com/python/cpython/pull/25916"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1995162"},{"url":"https://github.com/python/cpython/pull/26503"},{"url":"https://ubuntu.com/security/CVE-2021-3737"},{"url":"https://www.oracle.com/security-alerts/cpujul2022.html"},{"url":"https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html"},{"url":"https://security.netapp.com/advisory/ntap-20220407-0009/"},{"url":"https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html","name":"[debian-lts-announce] 20230524 [SECURITY] [DLA 3432-1] python2.7 security update","tags":["mailing-list"]},{"url":"https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html","name":"[debian-lts-announce] 20230630 [SECURITY] [DLA 3477-1] python3.7 security update","tags":["mailing-list"]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-835","type":"CWE","lang":"en","description":"CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop'), CWE-400 - Uncontrolled Resource Consumption"}]}],"providerMetadata":{"shortName":"redhat","orgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateUpdated":"2023-06-30T00:00:00.000Z"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://bugs.python.org/issue44022","tags":["x_transferred"]},{"url":"https://github.com/python/cpython/pull/25916","tags":["x_transferred"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1995162","tags":["x_transferred"]},{"url":"https://github.com/python/cpython/pull/26503","tags":["x_transferred"]},{"url":"https://ubuntu.com/security/CVE-2021-3737","tags":["x_transferred"]},{"url":"https://www.oracle.com/security-alerts/cpujul2022.html","tags":["x_transferred"]},{"url":"https://python-security.readthedocs.io/vuln/urllib-100-continue-loop.html","tags":["x_transferred"]},{"url":"https://security.netapp.com/advisory/ntap-20220407-0009/","tags":["x_transferred"]},{"url":"https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html","name":"[debian-lts-announce] 20230524 [SECURITY] [DLA 3432-1] python2.7 security update","tags":["mailing-list","x_transferred"]},{"url":"https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html","name":"[debian-lts-announce] 20230630 [SECURITY] [DLA 3477-1] python3.7 security update","tags":["mailing-list","x_transferred"]},{"url":"https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html"},{"url":"https://lists.debian.org/debian-lts-announce/2024/11/msg00024.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T21:45:09.305Z"}},{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2025-12-17T21:32:43.233615Z","id":"CVE-2021-3737","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-12-17T21:32:47.732Z"}},{"affected":[{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.0","status":"affected","lessThan":"V3.1.5","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.0","status":"affected","lessThan":"V3.1.5","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.0","status":"affected","lessThan":"V3.1.5","versionType":"custom"}]},{"vendor":"Siemens","product":"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.0","status":"affected","lessThan":"V3.1.5","versionType":"custom"}]},{"vendor":"Siemens","product":"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP","defaultStatus":"unknown","versions":[{"version":"V3.1.0","status":"affected","lessThan":"V3.1.5","versionType":"custom"}]}],"references":[{"url":"https://cert-portal.siemens.com/productcert/html/ssa-398330.html"}],"providerMetadata":{"shortName":"siemens-SADP","orgId":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e","dateUpdated":"2026-10-14T09:49:50.701Z"},"x_adpType":"supplier"}]}}}