{"id":"CVE-2026-97688","revision":"babe72b149bf4079a6524e2956715ea7","records":[{"revision":"babe72b149bf4079a6524e2956715ea7","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-97688","aliases":[],"title":"urllib3: Chunked Deflate streaming can enter an infinite loop","description":"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-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.","state":0,"publishedAt":"2026-09-29T15:32:17.622+00:00","modifiedAt":"2026-09-29T15:42:34.502+00:00","affected":[{"ecosystem":"Vendor product","name":"urllib3","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"urllib3\",\n                    \"product\": \"urllib3\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 2.6.2, < 2.8.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":6.9,"severity":"MEDIUM"}],"references":["https://github.com/urllib3/urllib3/security/advisories/GHSA-gh4c-6fx4-qh6g","https://github.com/urllib3/urllib3/commit/ea2ad7b21a80da3632f80016526a18864586077f","https://github.com/urllib3/urllib3/releases/tag/2.8.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-97688","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-97688","identifiers":["CVE-2026-97688"]},"retained":false,"historicalAffected":[]}],"coverage":[]}