{"id":"CVE-2026-111101","title":"HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit","summary":"Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte ch…","severity":"high","cvss":8.7,"cvssVector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","cvssSource":"cna","cwe":["CWE-770"],"vendor":"mtrudel","product":"bandit","affected":["bandit >= 0.1.0 < 1.14.0","mtrudel/bandit >= 7201270c34b90f6c9e15c0386c2bb802c0c72ab4 < 220b9dfd27f9a21305be2afc75cbe585ddc24e7a"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-10-26T15:10:33.224480Z"},"published":"2026-10-26","updated":"2026-10-26","sourceUpdated":"2026-10-26T15:35:51.401Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-111101","references":[{"url":"https://github.com/mtrudel/bandit/security/advisories/GHSA-jwh3-j29h-qfmw","label":"HTTP/1.1 chunked request bodies made of 1-byte chunks amplify memory use in Bandit"},{"url":"https://cna.erlef.org/cves/CVE-2026-111101.html","label":"EEF CNA record for CVE-2026-111101"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-111101","label":"OSV record EEF-CVE-2026-111101"},{"url":"https://github.com/mtrudel/bandit/commit/7201270c34b90f6c9e15c0386c2bb802c0c72ab4","label":"Introducing commit 7201270 in mtrudel/bandit"},{"url":"https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a","label":"Fix commit 220b9df in mtrudel/bandit"}],"tags":["cve.org"],"ingestedAt":"2026-10-26T14:27:31.818Z","slug":"CVE-2026-111101","body":"## Overview\n\nAllocation of Resources Without Limits or Throttling vulnerability in the HTTP/1.1 chunked body reader of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory and CPU via a request body made of many 1-byte chunks.\n\nThe chunked reader in lib/bandit/http1/socket.ex keeps every chunk as its own list cell and binary term until IO.iodata_to_binary/1 joins them, and nothing limits the number of chunks. The :length option of read_body/2 counts only data bytes, so tiny chunks cost far more memory than their payload: 48 MB of 1-byte chunks grew one handler process to about 500 MB and took about 6 s of CPU. The route does not need to read the body, because on keep-alive connections ensure_completed/1 drains unread bodies through the same reader.\n\nThis issue affects bandit: from 0.1.0 before 1.14.0.\n\n## Affected\n\n- `bandit >= 0.1.0 < 1.14.0`\n- `mtrudel/bandit >= 7201270c34b90f6c9e15c0386c2bb802c0c72ab4 < 220b9dfd27f9a21305be2afc75cbe585ddc24e7a`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n### Workarounds\n\nFrom 0.7.0, a server whose clients and proxies all speak HTTP/2 can disable HTTP/1 with http_1_options: [enabled: false], so that the vulnerable chunked body reader never runs.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":47.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}