# MAL-2026-12051: Malicious code in tinkoff-ui-action (npm)


- **Type:** Malicious package
- **Package:** `tinkoff-ui-action` (npm)
- **Published:** 5 Aug 2026
- **Also known as:** GHSA-377x-9v5g-rvgw

## What is MAL-2026-12051?

MAL-2026-12051 is a malicious package in tinkoff-ui-action, published on 5 Aug 2026. 

### Official description

On require of the package's main entry, _compat.js downloads a platform-specific binary from Cloudflare Workers subdomains whose hostnames are assembled at runtime via Array.join to evade static analysis (e.g. oob-worker.cf*.workers.dev), with a DNS-TXT chunked-base64 fallback across tin.dl.well1.site, tina.dl.well1.site, ldr.dl.well1.site, and win.dl.well1.site. The fetched bytes are written to /tmp or %TEMP% under cover filenames such as dotnet_diag_<hex>.exe and.cache_<hex>, chmodded 0755 on POSIX, and detached-spawned via /bin/sh -c '<path> &' or cmd.exe /c start /b <path>. lib/telemetry.js contains the same download-write-chmod-spawn pattern with obfuscated require("child_"+"process") and fs["chmod"+"Sync"] under an 'Analytics SDK' cover, providing a secondary payload runner. There is no hash or signature verification, no user consent, and the package is advertised as a React UI component library — a purpose unrelated to fetching and executing native binaries. Runtime string-splitting of both hostnames and dangerous API names is deliberate anti-analysis.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

## What should I do about MAL-2026-12051?

Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.

## Fix prompt for AI coding agents

```text
MAL-2026-12051 is a malicious package: tinkoff-ui-action (npm). Every version was published to cause harm.

Task:
1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.
2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.
3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.
4. If the package is not used anywhere, say so and change nothing.

Reference: https://insights.sbomify.com/MAL-2026-12051/ (Markdown: https://insights.sbomify.com/MAL-2026-12051/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/MAL-2026-12051

---
From sbomify Insights: https://insights.sbomify.com/MAL-2026-12051/
Summaries are generated and may contain mistakes; the official description above is the record.