[Bug][cyber] False positive blocks standard software build request under Opus 5.5 (req_011CfTmJF9sX7yH1xuEvycWX)

Triage: kind cyber · domain general · flagging model Opus 5.5 · silent fallback to Opus 4.8 · severity session-halted (blocked authorized work) · reproducible: yes — server-side via the Request ID(s) below

Type: Cybersecurity safety-filter false positive · Work domain (heuristic): general

Why this is a false positive

The safety classifier flagged a standard software build request immediately after switching the active model to Opus 5.5. The underlying task involved routine compilation of a general application codebase without cybersecurity tools or malicious payload logic. Halting the session on a basic compilation command disrupts standard software development workflows.

A server-side safety/policy block fired during authorized, in-scope work in Claude Code. Filing as a false positive. Recurred 1× across 1 session(s); first seen 2026-09-27T10:11:49.166Z.

Request IDs (lookup-able server-side)

• req_011CfTmJF9sX7yH1xuEvycWX · answered by Opus 4.8 instead (2026-09-27T10:11:49.166Z)

Model fallback

Claude Code did not surface this block. claude-opus-5-5 refused the request (API refusal category cyber, scope session) and the CLI re-ran it on claude-opus-4-8 without asking. The work continued on the weaker model; the Request ID above is the refused call.

In-scope justification

False positive — in-scope, authorized security work; not out of scope. Filed automatically by claudit.

Block message

Opus 5.5's safeguards flagged this session. You may be seeing this for the first time on an Opus model: Opus 5.5 is more capable and has stronger safeguards as a result, which can sometimes flag non-cybersecurity work. We're improving these safeguards to reduce the amount of incorrectly flagged messages. Opus 4.8 is answering instead, or you can edit and retry with Opus 5.5. Send feedback with /feedback or learn more: https://support.claude.com/en/articles/8106465

Details: [cyber]
This reques

Environment: Claude Code, Linux. · Work domain: general

Related reports (same work session, linked)

Distinct false-positive blocks from the same work session, each its own report:
#97599

Anthropic feedback id: 9ef60f7a-1ad9-4803-8662-138f34c78490

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_{🔎 Filed automatically by ClAudit v2.12.2 — a FOSS tool for reporting false-positive Claude Code blocks.}