{"id":"CVE-2025-66418","state":"PUBLISHED","title":"urllib3 allows an unbounded number of links in the decompression chain","description":"urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.","publishedAt":"2025-12-05T16:02:15.271Z","updatedAt":"2025-12-05T18:15:28.505Z","severity":{"score":8.9,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["urllib3 urllib3"],"affected":[{"vendor":"urllib3","product":"urllib3","versions":[{"version":">= 1.24, < 2.6.0","status":"affected"}]}],"references":["https://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53","https://github.com/urllib3/urllib3/commit/24d7b67eac89f94e11003424bcf0d8f7b72222a8"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:09:56.034Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/66xxx/CVE-2025-66418.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-66418","state":"PUBLISHED","datePublished":"2025-12-05T16:02:15.271Z","dateUpdated":"2025-12-05T18:15:28.505Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2025-11-28T23:33:56.367Z"},"containers":{"cna":{"title":"urllib3 allows an unbounded number of links in the decompression chain","descriptions":[{"lang":"en","value":"urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0."}],"affected":[{"vendor":"urllib3","product":"urllib3","versions":[{"version":">= 1.24, < 2.6.0","status":"affected"}]}],"references":[{"url":"https://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53","name":"https://github.com/urllib3/urllib3/security/advisories/GHSA-gm62-xv2j-4w53","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/urllib3/urllib3/commit/24d7b67eac89f94e11003424bcf0d8f7b72222a8","name":"https://github.com/urllib3/urllib3/commit/24d7b67eac89f94e11003424bcf0d8f7b72222a8","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"HIGH","baseScore":8.9,"baseSeverity":"HIGH","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H","version":"4.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2025-12-05T18:15:28.505Z"},"source":{"advisory":"GHSA-gm62-xv2j-4w53","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-12-05T16:15:39.701596Z","id":"CVE-2025-66418","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":"2025-12-05T16:16:08.790Z"}}]}}}