{"id":"CVE-2026-9375","summary":"Decompression Bomb Bypass via Negative max_length in Streaming API in urllib3","details":"urllib3 version 2.6.3 is vulnerable to a decompression bomb bypass in its streaming API (`preload_content=False`) when using Brotli support. The issue arises due to three independent code paths in `response.py` that bypass the `max_length` protection introduced in version 2.6.0 to mitigate CVE-2025-66471. Specifically, negative `max_length` values can be produced due to buffer arithmetic in `read()`, `flush_decoder` unconditionally overrides `max_length` to `-1`, and `_flush_decoder()` passes no limit at all, defaulting to unlimited decompression. This allows a malicious HTTP server to trigger an out-of-memory (OOM) condition by decompressing large payloads into memory, leading to a denial of service (DoS). The vulnerability affects urllib3 2.6.3 and Brotli 1.2.0 and impacts applications and libraries using `requests` or `urllib3` to stream content from untrusted sources.","modified":"2026-07-08T08:13:42.590417786Z","published":"2026-06-19T18:45:10.409Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9375.json","cwe_ids":["CWE-400"],"cna_assigner":"@huntr_ai"},"references":[{"type":"WEB","url":"https://huntr.com/bounties/ddd09eb9-b87d-4a43-84df-48837b1bbc23"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9375.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-9375"},{"type":"FIX","url":"https://github.com/urllib3/urllib3/commit/2bdcc44d1e163fb5cc48a8662425e35e15adfe6a"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/urllib3/urllib3","events":[{"introduced":"0"},{"fixed":"2bdcc44d1e163fb5cc48a8662425e35e15adfe6a"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"2.7.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["2.6.3","2.6.2","2.6.1","2.6.0","2.5.0","2.4.0","2.3.0","2.2.3","2.2.2","2.2.1","2.2.0","2.1.0","2.0.6","v2.0.5","2.0.5","2.0.4","2.0.3","2.0.2","2.0.1","2.0.0","2.0.0a4","2.0.0a3","2.0.0a2","2.0.0a1","1.25.8","1.25.7","1.25.6","1.25.5","1.25.4","1.25.3","1.25.2","1.25.1","1.25","1.7.1","1.7","1.6","1.5","1.4","1.3","1.2.1","1.2","1.1","0.4.1","0.4","0.3.1","0.3"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-9375.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}