{"id":"CVE-2026-97688","title":"urllib3 is an HTTP client library for Python","summary":"urllib3 is an HTTP client library for Python. From 2.6.2 until 2.8.0, HTTPResponse.stream and HTTPResponse.read_chunked can enter an infinite loop because the Deflate decoder retains trailing bytes as unconsumed input after reaching end-…","severity":"medium","cvss":6.9,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","cwe":["CWE-835"],"vendor":"urllib3","product":"urllib3","affected":["urllib3 >= 2.6.2, < 2.8.0"],"published":"2026-09-29","updated":"2026-09-29","sourceUpdated":"2026-09-29T16:17:18.680","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-97688","references":[{"url":"https://github.com/urllib3/urllib3/commit/ea2ad7b21a80da3632f80016526a18864586077f","label":"security-advisories@github.com"},{"url":"https://github.com/urllib3/urllib3/releases/tag/2.8.0","label":"security-advisories@github.com"},{"url":"https://github.com/urllib3/urllib3/security/advisories/GHSA-gh4c-6fx4-qh6g","label":"security-advisories@github.com"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-09-29T15:42:28.931695Z"},"cvssSource":"cna","ingestedAt":"2026-09-29T16:39:33.273Z","slug":"CVE-2026-97688","body":"## Overview\n\nurllib3 is an HTTP client library for Python. From 2.6.2 until 2.8.0, HTTPResponse.stream and HTTPResponse.read_chunked can enter an infinite loop because the Deflate decoder retains trailing bytes as unconsumed input after reaching end-of-stream and repeatedly decodes them without progress. The issue occurs when an untrusted server sends a chunked Deflate response whose decoded body exceeds a positive finite chunk size and whose encoded body has trailing bytes, specifically a response with Transfer-Encoding: chunked and Content-Encoding: deflate, content decoding enabled, and the positive finite amt=N streaming chunk size. The attack mechanism is that a malicious server returns a compressed chunked response with trailing bytes after the Deflate stream. The impact is excessive CPU usage and a request that does not complete, and network read timeouts do not interrupt the loop because no further socket read occurs. This issue is fixed in version 2.8.0.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":38,"depthScoreParts":{"impact":38,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}