{"id":"CVE-2026-75484","summary":"HTTP/2 header field values containing CR, LF or NUL are passed to the application unvalidated in Bandit","details":"Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in mtrudel bandit allows an unauthenticated remote attacker to smuggle CR, LF, or NUL characters into application-visible request headers via HTTP/2. Bandit.HTTP2.Stream.read_headers/1 validates pseudo-header placement and uniqueness, header-name casing, connection-specific headers, the te value, and content-length, but never checks field values. Because HPACK carries arbitrary octets, a HEADERS block whose field values contain \\r, \\n, or \\0 decodes without error and the values land in conn.req_headers unchanged. The HTTP/1 path already rejects the same octets; HTTP/2 did not.\n\nBandit itself is not a sink for the injected bytes: its own logging uses fixed strings or inspect, and HTTP/2 response headers are HPACK-encoded and separately rejected by Plug's put_resp_header, so response splitting is not reachable through this path. The risk is entirely in how a downstream application consumes header values, such as appending one verbatim to a plain-text log or concatenating it into an upstream request. A related gap bundled in the same fix: only :method, :scheme, and :path were checked for at most one occurrence; a duplicate :authority pseudo-header was accepted, with the first instance silently winning as conn.host while a conflicting value remained visible to the application.\n\nThis issue affects bandit: from 1.4.0 before 1.12.5.","aliases":["EEF-CVE-2026-75484","GHSA-x3gh-xhj4-3vq8"],"modified":"2026-08-27T11:30:55.686008594Z","published":"2026-08-20T21:11:27.523Z","database_specific":{"cwe_ids":["CWE-93"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75484.json","unresolved_ranges":[{"extracted_events":[{"introduced":"fff06efe3be962b484bd4d3eb339372fda5a231f"},{"fixed":"d38cf046c9a3cae4d0f88001c2ceb4143f86366b"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"EEF"},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-75484.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-75484"},{"type":"WEB","url":"https://repo.hex.pm"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75484.json"},{"type":"ADVISORY","url":"https://github.com/mtrudel/bandit/security/advisories/GHSA-x3gh-xhj4-3vq8"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-75484"},{"type":"FIX","url":"https://github.com/mtrudel/bandit/commit/d38cf046c9a3cae4d0f88001c2ceb4143f86366b"},{"type":"PACKAGE","url":"https://github.com/mtrudel/bandit"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mtrudel/bandit","events":[{"introduced":"e5d4262b07b3e1026c57647b281dccfababea13b"},{"fixed":"9571499ad29fbfbc465288764e2d91bece0eaff7"},{"fixed":"d38cf046c9a3cae4d0f88001c2ceb4143f86366b"}],"database_specific":{"source":["DESCRIPTION","REFERENCES"],"extracted_events":[{"introduced":"1.4.0"},{"fixed":"1.12.5"}]}}],"versions":["1.12.4","1.12.3","1.12.1","1.12.0","1.11.1","1.11.0","1.10.4","1.10.3","1.10.2","1.10.1","1.10.0","1.9.0","1.8.0","1.7.0","1.6.11","1.6.10","1.6.9","1.6.8","1.6.7","1.6.6","1.6.5","1.6.4","1.6.3","1.6.2","1.6.1","1.6.0","1.5.7","1.5.6","1.5.5","1.5.4","1.5.3","1.5.2","1.5.1","1.5.0","1.4.2","1.4.1","1.4.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-75484.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"}]}