MalwarePublished 6 Jun 2026Updated 9 Jul 2026

instructor-mcp (PyPI) · Malicious Code

Affects instructor-mcpSource GCVE Database

Malicious package : remove instructor-mcp and rotate any secrets on hosts that installed it.

Data as of 11 Jul 2026, 09:43 UTC

Classification

Malicious package

Published to PyPI · OSV MAL-2026-5317

What to do

Remove instructor-mcp from every project, lockfile and image that pulls it in. Treat any host that installed it as compromised: rotate the credentials, tokens and keys it could read, from a clean machine.

Affected software

Product	Affected	Fixed in
PyPIinstructor-mcp	Affected =1.15.2 =1.15.3	Fixed in–

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Description

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (6db8a103a73261cd6de8f763fa639d1bd148124ca661893e9d3ab73cd76ab50b) instructor-mcp 1.15.2 is a typosquat of the legitimate `instructor` PyPI library (it copies the same author names, README, and repository URL `github.com/instructor-ai/instructor`) and ships an additional file `instructor-setup.pth` that the Python interpreter auto-executes on every `python` invocation after install. The.pth file uses an obfuscated single-line `exec(...)` with mangled aliases (`_o,_s,_u,_p,_y,_h,_g`) to bypass the `.pth` rule that only `import` lines execute. The exec body downloads the Bun JavaScript runtime from `https://github.com/oven-sh/bun/releases/download/bun-v1.3.13/bun-{platform}-{arch}.zip` to `/tmp/b/bun`, chmods it executable, then searches `sys.path` for a file named `_index.js` and runs it via `bun run _index.js`. Execution is gated by `/tmp/.bun_ran` so it fires once per host. There is no hash/signature check on the downloaded runtime, and the JS payload is whatever `_index.js` happens to be present on `sys.path` (shipped by a co-installed package or planted by a separate component) — bypassing Python static analysis entirely. This is the alternate-runtime-dropper pattern: arbitrary attacker-controlled JS is executed under a freshly downloaded non-Python runtime, with persistence via the.pth auto-load mechanism. ## Source: kam193 (d22e882ab0d869a60fcff314b04f0534f3622d7719ed3a9101d55bb6c81dcbc9) Versions 1.15.2, 1.15.3 were compromised. Compromised packages start an obfuscated infostealer. The infostealer is a heavily obfuscated JavaScript code executed using Bun runtime on Python startup. It collectes all kinds of sensitive data, including API keys, credentials to package repositories, cryptocurrency assets, password manager data. Infostealer actively queries online services to collect additional secrets as well as attempts to gain persistence and spread further by publishing infected packages using collected credentials. Data are exfiltrated likely using Github. The code seems to threaten to wipe the user's data if it detects invalid GitHub tokens. Cleanup should be done with caution. It seems to be related to the recent Mini Shai Hulud campaign. --- Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers. Campaign: 2026-06-compr-woodpecker Reasons (based on the campaign): - compromised-package - exfiltration-env-variables - exfiltration-cloud-tokens - exfiltration-credentials - abuses-pth - obfuscation - infostealer - The package contains code to detect if it is running in a sandbox environment. - exfiltration-crypto - files-exfiltration - destructive-actions

Impact

This malicious package compromises user security by stealing sensitive information such as API keys, package repository credentials, cryptocurrency assets, and password manager data. It can exfiltrate data likely via GitHub and attempts to maintain persistence and spread by publishing infected packages. The destructive payload may wipe user data under certain conditions, posing a risk of data loss. The use of an alternate runtime (Bun JavaScript) bypasses Python security controls, increasing the difficulty of detection and mitigation.

Defensive guidance

Users should immediately uninstall instructor-mcp versions 1.15.2 and 1.15.3 if present. Avoid installing packages from untrusted or typosquatted sources. Exercise caution during cleanup to avoid triggering destructive payloads. Monitor for suspicious activity related to stolen credentials and consider rotating exposed secrets.

Summary

The instructor-mcp PyPI package versions 1.15.2 and 1.15.3 are compromised typosquats of the legitimate instructor package. They deploy a malicious .pth file that auto-executes on Python interpreter startup, running obfuscated code that downloads the Bun JavaScript runtime without integrity checks. This runtime executes a JavaScript infostealer payload (_index.js) that collects a wide range of sensitive information including environment variables, cloud tokens, credentials, cryptocurrency assets, and password manager data. The malware also attempts to maintain persistence and propagate by publishing infected packages using stolen credentials. It includes destructive functionality threatening to wipe user data if invalid GitHub tokens are found. The attack bypasses Python static analysis by executing code in an alternate runtime. This campaign is associated with the Mini Shai Hulud threat group and exhibits multiple malicious behaviors including sandbox detection, obfuscation, and data exfiltration.

References

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What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Jul 2026, 09:42 UTC

Technical details

References

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