{"abstract":"A backslash inside a redirect target reaches a different downstream parser.","category":"HTTP redirects","checks":6,"contract":"Validate raw target text before any URL normalization. The explicit fixture inputs and outputs define a bounded offline policy; request identity must accompany the decision.","contract_signature":"request, raw","evaluation_group":"s3-http-redirects-target-lexical-validation","failed_approach":"The partial repair uses \"raw.endswith('\\\\\\\\')\" and still fails an explicit boundary or control.","family":"s3-http-redirects-target-lexical-validation-backslash-rejection","id":"FA-27911","implementations":{"attempt":{"sha256":"b9dbdaf2c6be1debdbec55ed40c02fe0700f823a8e9133e3593627bcc11b3ef3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom urllib.parse import urlsplit, unquote, quote\nimport posixpath\nimport re\nN = 1\nobservations = []\ndef solve(request, raw):\n    return {'request': request, 'decision': ['\\r' in raw or '\\n' in raw, '\\t' in raw.strip(' \\t'), '\\x00' in raw, bool(re.search(r'%(?![0-9A-Fa-f]{2})', raw)), raw.endswith('\\\\')]} \ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve('/requests/' + str(N) + '/0', '/a\\rb\\tc\\x00d%G0\\\\e'), {'request': '/requests/' + str(N) + '/0', 'decision': [True, True, True, True, True]})\ncheck('fixture 2', solve('/requests/' + str(N) + '/1', '\\t/a%20b\\t'), {'request': '/requests/' + str(N) + '/1', 'decision': [False, False, False, False, False]})\ncheck('fixture 3', solve('/requests/' + str(N) + '/2', '/a\\nb'), {'request': '/requests/' + str(N) + '/2', 'decision': [True, False, False, False, False]})\ncheck('fixture 4', solve('/requests/' + str(N) + '/3', '/a%'), {'request': '/requests/' + str(N) + '/3', 'decision': [False, False, False, True, False]})\ncheck('fixture 5', solve('/requests/' + str(N) + '/4', '/normal'), {'request': '/requests/' + str(N) + '/4', 'decision': [False, False, False, False, False]})\ncheck('fixture 6', solve('/requests/' + str(N) + '/5', ''), {'request': '/requests/' + str(N) + '/5', 'decision': [False, False, False, False, False]})\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"b6bc221d5d247c95427ad397760fe78869bb6b98655375b8253933058d6044ff","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nfrom urllib.parse import urlsplit, unquote, quote\nimport posixpath\nimport re\nN = 1\nobservations = []\ndef solve(request, raw):\n    return {'request': request, 'decision': ['\\r' in raw or '\\n' in raw, '\\t' in raw.strip(' \\t'), '\\x00' in raw, bool(re.search(r'%(?![0-9A-Fa-f]{2})', raw)), raw.startswith('\\\\')]} \ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1', solve('/requests/' + str(N) + '/0', '/a\\rb\\tc\\x00d%G0\\\\e'), {'request': '/requests/' + str(N) + '/0', 'decision': [True, True, True, True, True]})\ncheck('fixture 2', solve('/requests/' + str(N) + '/1', '\\t/a%20b\\t'), {'request': '/requests/' + str(N) + '/1', 'decision': [False, False, False, False, False]})\ncheck('fixture 3', solve('/requests/' + str(N) + '/2', '/a\\nb'), {'request': '/requests/' + str(N) + '/2', 'decision': [True, False, False, False, False]})\ncheck('fixture 4', solve('/requests/' + str(N) + '/3', '/a%'), {'request': '/requests/' + str(N) + '/3', 'decision': [False, False, False, True, False]})\ncheck('fixture 5', solve('/requests/' + str(N) + '/4', '/normal'), {'request': '/requests/' + str(N) + '/4', 'decision': [False, False, False, False, False]})\ncheck('fixture 6', solve('/requests/' + str(N) + '/5', ''), {'request': '/requests/' + str(N) + '/5', 'decision': [False, False, False, False, False]})\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Stipulated offline redirect policy, not a complete HTTP, browser, URL, cache, or security implementation. Numbered variants vary request correlation identity. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"s3-http-redirects-target-lexical-validation-backslash-rejection","generated_at":"2026-09-29T14:41:29.292785+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Models a redirect controller decision before following a target or exposing a redirect result.","root_cause":"The backslash-rejection decision uses \"raw.startswith('\\\\\\\\')\"; this violates the stipulated controller policy.","sha256":"bae64296ffccae9e803592ae762fe3218d3eeabe6ddfaf0170f3cffeea9ebeb3","title":"Validate raw target text before any URL normalization: backslash rejection · case 01","variant":1,"variant_policy":"N changes request correlation identity. Policy boundary fixtures are reused; numbered variants are not independent examples.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":38.413,"exit_code":1,"observations":[{"actual":{"decision":[true,true,true,true,false],"request":"/requests/1/0"},"check":"fixture 1","expected":{"decision":[true,true,true,true,true],"request":"/requests/1/0"},"passed":false},{"actual":{"decision":[false,false,false,false,false],"request":"/requests/1/1"},"check":"fixture 2","expected":{"decision":[false,false,false,false,false],"request":"/requests/1/1"},"passed":true},{"actual":{"decision":[true,false,false,false,false],"request":"/requests/1/2"},"check":"fixture 3","expected":{"decision":[true,false,false,false,false],"request":"/requests/1/2"},"passed":true},{"actual":{"decision":[false,false,false,true,false],"request":"/requests/1/3"},"check":"fixture 4","expected":{"decision":[false,false,false,true,false],"request":"/requests/1/3"},"passed":true},{"actual":{"decision":[false,false,false,false,false],"request":"/requests/1/4"},"check":"fixture 5","expected":{"decision":[false,false,false,false,false],"request":"/requests/1/4"},"passed":true},{"actual":{"decision":[false,false,false,false,false],"request":"/requests/1/5"},"check":"fixture 6","expected":{"decision":[false,false,false,false,false],"request":"/requests/1/5"},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": {\"request\": \"/requests/1/0\", \"decision\": [true, true, true, true, false]}, \"expected\": {\"request\": \"/requests/1/0\", \"decision\": [true, true, true, true, true]}, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": {\"request\": \"/requests/1/1\", \"decision\": [false, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/1\", \"decision\": [false, false, false, false, false]}, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": {\"request\": \"/requests/1/2\", \"decision\": [true, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/2\", \"decision\": [true, false, false, false, false]}, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": {\"request\": \"/requests/1/3\", \"decision\": [false, false, false, true, false]}, \"expected\": {\"request\": \"/requests/1/3\", \"decision\": [false, false, false, true, false]}, \"passed\": true}, {\"check\": \"fixture 5\", \"actual\": {\"request\": \"/requests/1/4\", \"decision\": [false, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/4\", \"decision\": [false, false, false, false, false]}, \"passed\": true}, {\"check\": \"fixture 6\", \"actual\": {\"request\": \"/requests/1/5\", \"decision\": [false, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/5\", \"decision\": [false, false, false, false, false]}, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.781,"exit_code":1,"observations":[{"actual":{"decision":[true,true,true,true,false],"request":"/requests/1/0"},"check":"fixture 1","expected":{"decision":[true,true,true,true,true],"request":"/requests/1/0"},"passed":false},{"actual":{"decision":[false,false,false,false,false],"request":"/requests/1/1"},"check":"fixture 2","expected":{"decision":[false,false,false,false,false],"request":"/requests/1/1"},"passed":true},{"actual":{"decision":[true,false,false,false,false],"request":"/requests/1/2"},"check":"fixture 3","expected":{"decision":[true,false,false,false,false],"request":"/requests/1/2"},"passed":true},{"actual":{"decision":[false,false,false,true,false],"request":"/requests/1/3"},"check":"fixture 4","expected":{"decision":[false,false,false,true,false],"request":"/requests/1/3"},"passed":true},{"actual":{"decision":[false,false,false,false,false],"request":"/requests/1/4"},"check":"fixture 5","expected":{"decision":[false,false,false,false,false],"request":"/requests/1/4"},"passed":true},{"actual":{"decision":[false,false,false,false,false],"request":"/requests/1/5"},"check":"fixture 6","expected":{"decision":[false,false,false,false,false],"request":"/requests/1/5"},"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": {\"request\": \"/requests/1/0\", \"decision\": [true, true, true, true, false]}, \"expected\": {\"request\": \"/requests/1/0\", \"decision\": [true, true, true, true, true]}, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": {\"request\": \"/requests/1/1\", \"decision\": [false, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/1\", \"decision\": [false, false, false, false, false]}, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": {\"request\": \"/requests/1/2\", \"decision\": [true, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/2\", \"decision\": [true, false, false, false, false]}, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": {\"request\": \"/requests/1/3\", \"decision\": [false, false, false, true, false]}, \"expected\": {\"request\": \"/requests/1/3\", \"decision\": [false, false, false, true, false]}, \"passed\": true}, {\"check\": \"fixture 5\", \"actual\": {\"request\": \"/requests/1/4\", \"decision\": [false, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/4\", \"decision\": [false, false, false, false, false]}, \"passed\": true}, {\"check\": \"fixture 6\", \"actual\": {\"request\": \"/requests/1/5\", \"decision\": [false, false, false, false, false]}, \"expected\": {\"request\": \"/requests/1/5\", \"decision\": [false, false, false, false, false]}, \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}