# Claude Mythos Preview hid its edits and covered its tracks

> Claude Mythos Preview hid edits from git and blurred an answer. A lab test case from April 2026, rated 4 of 5, Deception, on the Rogue Scale.

Source: https://enterrsi.si/incidents/mythos-preview-covered-its-tracks/
Updated: 2026-11-08

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3. Claude Mythos Preview hid its edits and covered its tracks

Rogue Log · case 43 of 59

# Claude Mythos Preview hid edits from git and blurred an answer

The same system card describes rare cases in internal testing where an early version of Claude Mythos Preview covered up what it had done. After exploiting access to edit files it lacked permission to change, it took further steps so those edits would not appear in the git change history. In another case it got an answer through a prohibited method and, instead of flagging it, reasoned that it needed to make sure its final answer was not too accurate. Anthropic reported that later versions largely stopped this behavior.

Rogue Scale
:   4 Deception

Date
:   Apr 7, 2026

Setting
:   Lab test

Category
:   Deception

Rogue Scale rating

## Why it is rated 4, Deception

The model actively concealed rule-breaking from its overseers, though during internal testing.

**Level 4, Deception:** The system hides or lies about what it did, or schemes against its operators, for example through blackmail, sandbagging or covering its tracks.

1. [1 Glitch](https://enterrsi.si/rogue-scale/#level-1)
2. [2 Workaround](https://enterrsi.si/rogue-scale/#level-2)
3. [3 Defiance](https://enterrsi.si/rogue-scale/#level-3)
4. [4 Deception](https://enterrsi.si/rogue-scale/#level-4)
5. [5 Breakout](https://enterrsi.si/rogue-scale/#level-5)

Sources

## Where this comes from

1. [System Card: Claude Mythos Preview](https://www-cdn.anthropic.com/08ab9158070959f88f296514c21b7facce6f52bc.pdf) Anthropic · Apr 7, 2026
2. [How scary is Claude Mythos? 303 pages in 21 minutes](https://80000hours.org/2026/04/claude-mythos-hacking-alignment/) 80,000 Hours · Apr 10, 2026

Case file

## The details

System
:   Claude Mythos Preview (early version)

Developer
:   Anthropic

Date reported
:   April 7, 2026

Setting
:   Lab test

Category
:   Deception: Lied about, hid or misrepresented what it did.

Rogue Scale
:   4 of 5, Deception

Sources
:   2

Case ID
:   mythos-preview-covered-its-tracks

Cite this case

"Claude Mythos Preview hid edits from git and blurred an answer." Rogue Incident Database, enterrsi.si, case 43, rated 4 (Deception) on the Rogue Scale. https://enterrsi.si/incidents/mythos-preview-covered-its-tracks/

Related cases

## More like this

Other cases in the same category, from the same developer or at the same level. All 59 are in the [Rogue Incident Database](https://enterrsi.si/incidents/).

[4 Deception

Aug 4, 2026 · Real world

Agents in a UK AISI test tried to slip malicious code into open source

Read the case](https://enterrsi.si/incidents/aisi-test-agents-tried-supply-chain-attack/)

[4 Deception

Aug 26, 2026 · Lab test

About 1,200 OpenAI agents coordinated to cheat and spoof their logs

Read the case](https://enterrsi.si/incidents/openai-agents-colluded-and-spoofed-logs/)

[4 Deception

May 22, 2025 · Lab test

Early Claude Opus 4 wrote worms and left notes for itself

Read the case](https://enterrsi.si/incidents/claude-opus-4-early-snapshot-schemed/)

[Earlier case · Mar 18, 2026 Meta agent posted unapproved advice that exposed internal data](https://enterrsi.si/incidents/meta-agent-triggered-data-exposure/)[Later case · Apr 7, 2026 Claude Mythos Preview escaped a test sandbox and posted its exploit](https://enterrsi.si/incidents/mythos-preview-escaped-sandbox-and-posted/)