{"schema_version":"0.10.0","id":"LR-2026-0443","record_version":1,"title":"Anthropic Claude Code source code leaked through npm packaging error","verification":{"human_verified":false,"method":"automated_gate","auto_verified":true,"score":55.1,"score_breakdown":{"source_authority":12.1,"independent_corroboration":15.0,"implicated_party_confirmed":0.0,"citation_integrity":14.0,"specificity":3.0,"completeness":3.52,"unhedged_language":4.69},"checks":{"schema_valid":true,"every_field_cited":true,"quotes_verbatim":true,"source_fetched":true,"distinct_incident":true,"dates_plausible":true,"sources_agree":true,"source_describes_incident":true,"severe_backed_by_source":true,"record_integrity":true,"eligible":true,"about_this_case":true},"gate_version":"gate-2026-10-18.7","cross_check_model":null,"cross_check_agreement":null,"duplicate_of":null,"verified_by":null,"verified_at":"2026-11-01","extraction_run_id":null,"evidence_level":{"level":"confirmed","reason":"2 independent outlets","original_document":null,"reports_total":2,"reports_independent":2,"reports_derivative":0,"developing":false,"disputed":false,"rules_version":"evidence-2026-10-29.1","computed_at":"2026-11-01","history":[{"date":"2026-11-01","from_level":null,"to_level":"confirmed","reason":"2 independent outlets"}]},"sources_hash":"a87e022b81caa07d1bcfb06f02a378bcc039d4ee67b2981cff0f9e4e4a264469"},"system":{"model_name":null,"model_version":null,"developer":"Anthropic","harness":null,"tools_granted":[],"permissions_scope":null,"autonomy_level":"unknown","guardrails_present":[],"deployment_context":"unknown","tier":null,"lifecycle_stage":null,"integration_type":null,"intended_use":"coding tool","safeguard_state":null,"production_intended":null},"event":{"date_occurred":null,"date_disclosed":"2026-03-31","incident_class":"operational_error","failure_class":null,"agent_involved":null,"secondary_failure_classes":[],"trigger":"unknown","duration":null,"detection_method":"unknown","summary":"Anthropic's Claude Code, a coding tool whose software harness wraps its underlying AI model, had its source code exposed publicly. Press reports say the leak exposed around 500,000 lines of code across roughly 1,900 files. The exposure appears to have followed an upload of all of Claude Code's original code to NPM rather than only the finished build. Anthropic said the matter was a release packaging issue caused by human error, not a security breach, and that no sensitive customer data or credentials were involved or exposed. Anthropic said normal release safeguards were not bypassed, while an outside security researcher said the process did not appear to be in place. The leak came days after a separate exposure of draft material, and Anthropic said it was rolling out measures to prevent recurrence.","tags":[],"date_detected":null,"near_miss":null,"root_cause":null,"root_cause_detail":"Release packaging issue caused by human error, per Anthropic","failure_class_detail":null,"responsible_party":null,"adversarial_actor":null,"input_provenance":null,"time_to_contain":null,"operations_paused":null,"remediation":"Rolling out measures to prevent recurrence","precursor_events":null},"impact":{"direct_loss_usd":null,"remediation_hours":null,"records_exposed":null,"third_parties_affected_count":null,"severity":"minor","severity_because":"Test: minor, contained to the company's own source code; no third-party data touched, per Anthropic's statement that no sensitive customer data or credentials were involved or exposed.","harm_class":[],"affected_description":"Anthropic's Claude Code source code, around 500,000 lines across roughly 1,900 files","protected_class_involved":null,"data_categories_exposed":[],"loss_range_usd":null,"reversibility":null,"downstream_exposure_count":null},"evidence":{"sources":[{"url":"https://fortune.com/2026/03/31/anthropic-source-code-claude-code-data-leak-second-security-lapse-days-after-accidentally-revealing-mythos/","publisher":"Fortune","date":"2026-03-31","type":"press","title":"Anthropic leaks its own AI coding tool’s source code in second major security breach - Fortune","archived_url":null,"attachment":"first_report","independence":"independent"},{"url":"https://startupfortune.com/claude-code-leak-reveals-anthropics-internal-playbook/","publisher":"Startup Fortune","date":"2026-03-31","type":"press","title":"Claude Code Leak Reveals Anthropic's Internal Playbook - Startup Fortune","archived_url":null,"independence":"independent"}],"per_field_confidence":{"system.developer":"C","system.intended_use":"C","impact.affected_description":"C","event.incident_class":"C","event.root_cause_detail":"C","event.remediation":"C","impact.severity":"D","impact.severity_because":"D","event.summary":"C","system.autonomy_level":"D","system.deployment_context":"D","event.trigger":"D","event.detection_method":"D","context.country":"D","event.date_disclosed":"D","context.denominator_available":"D"},"field_citations":{"system.developer":[{"source_index":0,"quote":"Anthropic has accidentally leaked the source code for its popular coding tool Claude Code."}],"system.intended_use":[{"source_index":0,"quote":"Anthropic has accidentally leaked the source code for its popular coding tool Claude Code."}],"impact.affected_description":[{"source_index":0,"quote":"The source code leak exposed around 500,000 lines of code across roughly 1,900 files."}],"event.incident_class":[{"source_index":0,"quote":"This was a release packaging issue caused by human error, not a security breach."}],"event.root_cause_detail":[{"source_index":0,"quote":"This was a release packaging issue caused by human error, not a security breach."}],"event.remediation":[{"source_index":0,"quote":"We’re rolling out measures to prevent this from happening again."}],"impact.severity":[{"source_index":0,"quote":"No sensitive customer data or credentials were involved or exposed."}],"impact.severity_because":[{"source_index":0,"quote":"No sensitive customer data or credentials were involved or exposed."}],"event.summary":[{"source_index":0,"quote":"Anthropic has accidentally leaked the source code for its popular coding tool Claude Code."},{"source_index":0,"quote":"The source code leak exposed around 500,000 lines of code across roughly 1,900 files."},{"source_index":0,"quote":"The newest leak, first made public in an X post, appears to have happened after Anthropic uploaded all of Claude Code’s original code to NPM, a platform developers use to share and update software, instead of only the finished version that computers actually run."},{"source_index":0,"quote":"This was a release packaging issue caused by human error, not a security breach."},{"source_index":0,"quote":"No sensitive customer data or credentials were involved or exposed."},{"source_index":0,"quote":"Anthropic told Fortune that normal release safeguards were not bypassed."},{"source_index":0,"quote":"At Anthropic, it seems that the process wasn't in place and a single misconfiguration or misclick suddenly exposed the full source code."},{"source_index":0,"quote":"We’re rolling out measures to prevent this from happening again."}]},"notes_on_gaps":"The sources do not state the date the source code was first exposed, so date_occurred and duration are omitted. Claude Code is a harness, not a model, so no model name or version is recorded. No autonomous agent acted in the leak, so agent_involved is set to false and no failure_class is given. The root cause is disputed: Anthropic says release safeguards were not bypassed, while Roy Paz says the process was not in place; root_cause is set to unknown. The trigger is not in the closed list (human error is not an option), so it is omitted. Detection method is not stated beyond a public X post, so it is omitted. Severity 'minor' is my judgement: Anthropic says no customer data or credentials were exposed, but the code was publicly visible, so the tier is uncertain. Harm class 'ip' is my judgement for proprietary source code. The remediation control B4 is my judgement, since Anthropic did not name the controls it added. Startup Fortune (source 1) was not used for facts because it contains unrelated content and unsupported details about the leak. No direct loss, record count or affected third-party count is stated. [case created by the backfill: read by claude-haiku-5-5, backfill-2026-11-01.2, 2026-11-01; not yet reviewed] [2026-11-01: evidence level set: Confirmed (2 independent outlets)]"},"context":{"industry":null,"org_size_band":null,"country":"unknown","denominator_available":false,"denominator":null,"related_incident_ids":[],"systemic_exposure":null,"shared_model_id":null,"upstream_incident_id":null,"incident_evidence":null,"regulatory":null,"coverage":null},"narrative":{"steps":[{"step":"reached","text":"When Fortune asked for comment, Anthropic confirmed that some internal source code had been leaked within a Claude Code release.","quote":"When reached for comment, Anthropic confirmed that “some internal source code” had been leaked within a “Claude Code release.”","source_index":0,"grade":"C"},{"step":"done","text":"Anthropic said it was rolling out measures to prevent this from happening again; no details of the measures are given.","quote":"We’re rolling out measures to prevent this from happening again.","source_index":0,"grade":"C"}],"model":"claude-haiku-5-5","prompt_version":"backfill-2026-11-01.2","extracted_at":"2026-11-01","source_urls":["https://fortune.com/2026/03/31/anthropic-source-code-claude-code-data-leak-second-security-lapse-days-after-accidentally-revealing-mythos/","https://startupfortune.com/claude-code-leak-reveals-anthropics-internal-playbook/"]},"analysis":{"sections":{"timeline":[{"text":"An early version of Claude Code accidentally exposed its original code in a similar breach.","quote":"In February 2025, an early version of Claude Code accidentally exposed its original code in a similar breach.","source_index":0,"when":"2025-02"},{"text":"Anthropic confirmed to Fortune that some internal source code had been leaked within a Claude Code release.","quote":"When reached for comment, Anthropic confirmed that “some internal source code” had been leaked within a “Claude Code release.”","source_index":0,"when":null},{"text":"Anthropic said it was rolling out measures to prevent this from happening again.","quote":"We’re rolling out measures to prevent this from happening again.","source_index":0,"when":null}]},"model":"claude-haiku-5-5","prompt_version":"backfill-2026-11-01.2","extracted_at":"2026-11-01","source_urls":["https://fortune.com/2026/03/31/anthropic-source-code-claude-code-data-leak-second-security-lapse-days-after-accidentally-revealing-mythos/","https://startupfortune.com/claude-code-leak-reveals-anthropics-internal-playbook/"]}}