GPT-6.1 Sol (effort default (no reasoning-effort override) · thinking on) on Fix catastrophic-backtracking (ReDoS) regexes in signup validators without changing what they accept
OGPT-6.1 Soldefault · thinking on · Codex CLI 0.163.0 (codex exec --json) · cloud · 2026-10-22 · by @bobsiopener
- Estimated cost
- $0.05
- Wall time
- 1m
- Human step-ins
- 0
- Outcome
- Pass
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Summary
Exact prompt
# Task: fix a ReDoS in the signup validators A pen-test found that crafted inputs make `validate.py` hang the API worker (catastrophic regex backtracking). Make all three validators run in linear-ish time on any input up to 100 KB, **without changing which inputs they accept**: for every input the original accepts or rejects in reasonable time, your version must return the same answer. Notes: `is_username` should accept exactly what the original accepts (word characters with single optional whitespace separators, max 64 chars) - including the empty string. Keep function names/signatures. Python stdlib only (`re` is fine; so is not using regex at all). Write `SECURITY_FIX.md` (2+ lines). No network.
Easy to make fast, hard to keep the exact accepted language: trailing-separator locals, the `$`-before-final-newline quirk, unicode \w, the 64-char cap and empty-string acceptance are all compared against the original. Original benchmark task written for usecaserank.com. Headless, offline run on a reproducible fixture. Cost shown is a list-price API-equivalent estimate (run on a ChatGPT subscription, not billed).
Success criteria: 1. same_accept_reject: is_email/is_username/is_tag_list return the same result as the original on 10,619 validator calls (fixed edge cases + seeded random strings; strings over 20 chars only for is_username because the original is exponential there). 2. linear_time: on 10 crafted inputs up to 100 KB (x3 validators) the slowest call takes < 0.25 s (subprocess capped at 20 s). 3. notes_present: SECURITY_FIX.md has at least 2 lines.
Setup notes: Use Case Scout batch5 case e09-redos-validator (offline fixture). Prepared with batch5/prepare.sh on the shared box; only TASK.md + starting files were copied to the agent machine, hidden key/tests stayed on the box. Prompt = TASK.md verbatim on stdin. Flags: --json -s workspace-write --skip-git-repo-check --ephemeral --ignore-user-config --ignore-rules -C <workdir>. Scored on the box with the scout's scorer: `python score.py WORKDIR KEYDIR`. Single run, no retries. User-level AGENTS.md (846 bytes, sha256 83ec4fe50da8) may have been in context; --ignore-user-config does not document excluding it. Serving model not confirmed: requested via -m; the event log does not echo the serving model id. Price source is secondary (pricing.json verification='secondary', https://www.actuia.com/en/news/ai-api-pricing-in-october-2026-050-to-50-for-output/), not an official OpenAI price page. Score: 3/3 checks. Cost is an ESTIMATE: measured tokens x pricing.json list price (ChatGPT plan, nothing billed); input_tokens include cached reads; output_tokens include reasoning tokens. Tool calls 4 (2 failed, recovered). Single run.
Estimated cost List-price estimate; not actually billed.
Metrics
- Estimated cost
- $0.05
- Wall time
- 1m
- Human step-ins
- 0
- Turns
- 1
| Model | Input tok | Output tok | Cost |
|---|---|---|---|
| OGPT-6.1 Solopenai/gpt-6.1-soleffort default (no reasoning-effort override) · thinking on | 100,132 | 2,089 | $0.05 |
Reproduce this run
- Use the use case prompt on the use case page.
- Same setup: GPT-6.1 Sol (openai/gpt-6.1-sol, effort default (no reasoning-effort override) · thinking on) via
Codex CLI 0.163.0 (codex exec --json), cloud. - It counts as a success only if it meets every success criterion: 1. same_accept_reject: is_email/is_username/is_tag_list return the same result as the original on 10,619 validator calls (fixed edge cases + seeded random strings; strings over 20 chars only for is_username because the original is exponential there). 2. linear_time: on 10 crafted inputs up to 100 KB (x3 validators) the slowest call takes < 0.25 s (subprocess capped at 20 s). 3. notes_present: SECURITY_FIX.md has at least 2 lines.
- Log model, tokens, wall time, human step-ins and the evidence log, then submit it as a reproduction. A different model? Submit a head-to-head rerun.
How runs are scored: Methodology.
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Automated checks
Trust 80% comes from these checks (how Trust % works).
- Run date is not in the future : passed
- Model is in the dated pricing table : passed
- Cost recomputed from tokens matches : passed
- Cached tokens are consistent : passed
- Output throughput is plausible : passed
- Autonomy matches step-ins : passed
- Step-ins do not exceed turns : passed
- Retries agree with first-try result : passed
- Evidence log SHA-256 matches : passed
- Evidence log is substantial : passed
Evidence log
{"type": "thread.started", "thread_id": "01a16433-56e9-7b22-b52c-f5aaaed8b079"}
{"type": "turn.started"}
{"type": "item.completed", "item": {"id": "item_0", "type": "agent_message", "text": "I\u2019ll inspect the validators, preserve their acceptance behavior, and check adversarial inputs without using the network.\n"}}
{"type": "item.started", "item": {"id": "item_1", "type": "command_execution", "command": "/bin/bash -lc \"pwd; rg --files -g 'AGENTS.md' -g '*validate*' -g '*test*' -g 'pyproject.toml' -g 'README*'\"", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_1", "type": "command_execution", "command": "/bin/bash -lc \"pwd; rg --files -g 'AGENTS.md' -g '*validate*' -g '*test*' -g 'pyproject.toml' -g 'README*'\"", "aggregated_output": "/home/bob/usecase-runs/batch/out/gpt-6.1-sol/167_e09/work\nvalidate.py\n", "exit_code": 0, "status": "completed"}}
{"type": "item.started", "item": {"id": "item_2", "type": "command_execution", "command": "/bin/bash -lc 'cat validate.py; ls -la; git status --short'", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_2", "type": "command_execution", "command": "/bin/bash -lc 'cat validate.py; ls -la; git status --short'", "aggregated_output": "\"\"\"Input validators used by the signup API. Each returns True/False.\"\"\"\nimport re\n\nEMAIL = re.compile(r\"^([a-zA-Z0-9]+[._+-]?)+@([a-zA-Z0-9]+(-[a-zA-Z0-9]+)*\\.)+[a-zA-Z]{2,}$\")\nUSERNAME = re.compile(r\"^(\\w+\\s?)*$\")\nTAGS = re.compile(r\"^(#?[a-z0-9]+,?)+$\")\n\ndef is_email(s):\n return bool(EMAIL.match(s))\n\ndef is_username(s):\n return len(s) <= 64 and bool(USERNAME.match(s))\n\ndef is_tag_list(s):\n return bool(TAGS.match(s))\ntotal 16\ndrwxr-xr-x 6 bob bob 4096 Oct 22 11:20 .\ndrwxrwxr-x 3 bob bob 4096 Oct 22 11:20 ..\ndr-xr-xr-x 2 bob bob 40 Oct 22 11:20 .agents\ndr-xr-xr-x 2 bob bob 40 Oct 22 11:20 .aws\ndr-xr-xr-x 2 bob bob 40 Oct 22 11:20 .codex\ndr-xr-xr-x 2 bob bob 40 Oct 22 11:20 .git\n-rw-r--r-- 1 bob bob 708 Oct 22 10:08 TASK.md\n-rw-r--r-- 1 bob bob 431 Oct 22 10:08 validate.py\nfatal: not a git repository (or any of the parent directories): .git\n", "exit_code": 128, "status": "failed"}}
{"type": "item.completed", "item": {"id": "item_3", "type": "agent_message", "text": "The patterns have ambiguous repeated groups that cause excessive backtracking. I\u2019ll replace them with equivalent patterns whose groups have clear boundaries, preserving the empty username, Unicode word and whitespace characters, trailing separators, and Python\u2019s special handling of a final newline.\n"}}
{"type": "item.started", "item": {"id": "item_4", "type": "file_change", "changes": [{"path": "/home/bob/usecase-runs/batch/out/gpt-6.1-sol/167_e09/work/SECURITY_FIX.md", "kind": "add"}, {"path": "/home/bob/usecase-runs/batch/out/gpt-6.1-sol/167_e09/work/validate.py", "kind": "update"}], "status": "in_progress"}}
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{"type": "item.started", "item": {"id": "item_5", "type": "command_execution", "command": "/bin/bash -lc \"cat > test_validate.py <<'PY'\nimport itertools\nimport re\nimport subprocess\nimport sys\nimport unittest\n\nimport validate\n\n\nclass ValidatorTests(unittest.TestCase):\n def test_original_languages(self):\n cases = [\n (validate.is_email,\n r'\"'^([a-zA-Z0-9]+[._+-]?)+@([a-zA-Z0-9]+(-[a-zA-Z0-9]+)*'\"\\\\.)+[a-zA-Z]{2,}\"'$'\"',\n 'a1._+-@\\\\n', 5),\n (validate.is_username, r'\"'^('\"\\\\w+\\\\s?)*\"'$'\"', 'a_\u00e9\u4e2d \\\\t\\\\n\"'!'\"', 5),\n (validate.is_tag_list, r'\"'^(#?[a-z0-9]+,?)+$'\"', 'a0#,A\\\\n', 6),\n ]\n for validator, pattern, alphabet, max_length in cases:\n original = re.compile(pattern)\n for length in range(max_length + 1):\n for chars in itertools.product(alphabet, repeat=length):\n value = ''.join(chars)\n self.assertEqual(validator(value), bool(original.match(value)),\n (validator.__name__, repr(value)))\n\n def test_email_examples(self):\n original = re.compile(r'\"'^([a-zA-Z0-9]+[._+-]?)+@([a-zA-Z0-9]+(-[a-zA-Z0-9]+)*'\"\\\\.)+[a-zA-Z]{2,}\"'$'\"')\n for local, domain, suffix in itertools.product(\n ['a', 'ab', 'a.', 'a+b_c-d.', 'a..b', '.a', 'a--b', '\u00e9'],\n ['a.co', 'ab-c.de', 'a.b.co', 'a--b.co', '-a.co', 'a.c', 'a.\u00e9\u00e9'],\n ['', '\\\\n', '\\\\n\\\\n', '\"'!'\"'],\n ):\n value = local + '@' + domain + suffix\n self.assertEqual(validate.is_email(value), bool(original.match(value)), value)\n\n def test_username_limit(self):\n self.assertTrue(validate.is_username(''))\n self.assertTrue(validate.is_username('a' * 64))\n self.assertFalse(validate.is_username('a' * 65))\n self.assertTrue(validate.is_username('a\\\\n\\\\n'))\n self.assertFalse(validate.is_username('a b'))\n\n def test_large_adversarial_inputs_finish(self):\n # A child process bounds the test even if backtracking is reintroduced.\n subprocess.run([sys.executable, '-c', '''\nimport validate\nfor value in ['a' * 102399 + '\"'!'\"', ('a.' * 51199) + '\"'!'\"',\n ('a-' * 51199) + '\"'!'\"', ('a,' * 51199) + '\"'!'\"',\n ('#a' * 51199) + '\"'!'\"', 'a' * 102400,\n 'a@' + 'a.' * 51198 + 'co', 'a@' + 'a.' * 51198 + '\"'!'\"']:\n for validator in [validate.is_email, validate.is_username, validate.is_tag_list]:\n validator(value)\n'''], check=True, timeout=5)\n\n\nif __name__ == '__main__':\n unittest.main()\nPY\npython -m unittest -v\"", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_5", "type": "command_execution", "command": "/bin/bash -lc \"cat > test_validate.py <<'PY'\nimport itertools\nimport re\nimport subprocess\nimport sys\nimport unittest\n\nimport validate\n\n\nclass ValidatorTests(unittest.TestCase):\n def test_original_languages(self):\n cases = [\n (validate.is_email,\n r'\"'^([a-zA-Z0-9]+[._+-]?)+@([a-zA-Z0-9]+(-[a-zA-Z0-9]+)*'\"\\\\.)+[a-zA-Z]{2,}\"'$'\"',\n 'a1._+-@\\\\n', 5),\n (validate.is_username, r'\"'^('\"\\\\w+\\\\s?)*\"'$'\"', 'a_\u00e9\u4e2d \\\\t\\\\n\"'!'\"', 5),\n (validate.is_tag_list, r'\"'^(#?[a-z0-9]+,?)+$'\"', 'a0#,A\\\\n', 6),\n ]\n for validator, pattern, alphabet, max_length in cases:\n original = re.compile(pattern)\n for length in range(max_length + 1):\n for chars in itertools.product(alphabet, repeat=length):\n value = ''.join(chars)\n self.assertEqual(validator(value), bool(original.match(value)),\n (validator.__name__, repr(value)))\n\n def test_email_examples(self):\n original = re.compile(r'\"'^([a-zA-Z0-9]+[._+-]?)+@([a-zA-Z0-9]+(-[a-zA-Z0-9]+)*'\"\\\\.)+[a-zA-Z]{2,}\"'$'\"')\n for local, domain, suffix in itertools.product(\n ['a', 'ab', 'a.', 'a+b_c-d.', 'a..b', '.a', 'a--b', '\u00e9'],\n ['a.co', 'ab-c.de', 'a.b.co', 'a--b.co', '-a.co', 'a.c', 'a.\u00e9\u00e9'],\n ['', '\\\\n', '\\\\n\\\\n', '\"'!'\"'],\n ):\n value = local + '@' + domain + suffix\n self.assertEqual(validate.is_email(value), bool(original.match(value)), value)\n\n def test_username_limit(self):\n self.assertTrue(validate.is_username(''))\n self.assertTrue(validate.is_username('a' * 64))\n self.assertFalse(validate.is_username('a' * 65))\n self.assertTrue(validate.is_username('a\\\\n\\\\n'))\n self.assertFalse(validate.is_username('a b'))\n\n def test_large_adversarial_inputs_finish(self):\n # A child process bounds the test even if backtracking is reintroduced.\n subprocess.run([sys.executable, '-c', '''\nimport validate\nfor value in ['a' * 102399 + '\"'!'\"', ('a.' * 51199) + '\"'!'\"',\n ('a-' * 51199) + '\"'!'\"', ('a,' * 51199) + '\"'!'\"',\n ('#a' * 51199) + '\"'!'\"', 'a' * 102400,\n 'a@' + 'a.' * 51198 + 'co', 'a@' + 'a.' * 51198 + '\"'!'\"']:\n for validator in [validate.is_email, validate.is_username, validate.is_tag_list]:\n validator(value)\n'''], check=True, timeout=5)\n\n\nif __name__ == '__main__':\n unittest.main()\nPY\npython -m unittest -v\"", "aggregated_output": "/bin/bash: line 61: python: command not found\n", "exit_code": 127, "status": "failed"}}
{"type": "item.started", "item": {"id": "item_6", "type": "command_execution", "command": "/bin/bash -lc 'python3 -m unittest -v'", "aggregated_output": "", "exit_code": null, "status": "in_progress"}}
{"type": "item.completed", "item": {"id": "item_6", "type": "command_execution", "command": "/bin/bash -lc 'python3 -m unittest -v'", "aggregated_output": "test_email_examples (test_validate.ValidatorTests.test_email_examples) ... ok\ntest_large_adversarial_inputs_finish (test_validate.ValidatorTests.test_large_adversarial_inputs_finish) ... ok\ntest_original_languages (test_validate.ValidatorTests.test_original_languages) ... ok\ntest_username_limit (test_validate.ValidatorTests.test_username_limit) ... ok\n\n----------------------------------------------------------------------\nRan 4 tests in 0.163s\n\nOK\n", "exit_code": 0, "status": "completed"}}
{"type": "item.completed", "item": {"id": "item_7", "type": "agent_message", "text": "Fixed all three validators with linear-time regex patterns while preserving accepted inputs, including empty usernames and final-newline behavior.\n\nAdded `SECURITY_FIX.md` and regression tests covering original-pattern equivalence and adversarial inputs up to 100 KB.\n\nVerification: `python3 -m unittest -v` \u2014 all 4 tests passed."}}
{"type": "turn.completed", "usage": {"input_tokens": 100132, "cached_input_tokens": 90624, "cache_write_input_tokens": 0, "output_tokens": 2089, "reasoning_output_tokens": 552}}