Malicious code in classbreeze-utils (npm)
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (e19daf4f946816f5ba3c6e592eacc980861b281c6752b738de57fdd31f49279d) The package masquerades as a Tailwind plugin: README and the top of src/index.js are a verbatim clone of @tailwindcss/typography (require('tailwindcss/plugin'), prose-* class generator), even though the package name has no relationship to Tailwind. Appended after the cloned plugin code at src/index.js:124+ is a heavily obfuscated IIFE using an RC4-decoded string array and AES-decipher key table to hide its strings and control flow. The decoded action table contains keys 'cmd.npx', 'cmd.npxwin', 'pkg.link', 'cmd.install', 'flag.yes', which are consumed by helpers that call child_process.spawn with detached:true, stdio:'ignore', windowsHide:true and creationFlags set to DETACHED_PROCESS to silently run `npx -y <pkg.link>`, fetching and executing an attacker-controlled package from the npm registry on the developer's machine. On Windows an additional path uses keys 'ext.vbs', 'vbs.tag', 'win.wscript': a VBS file is written to os.tmpdir() with a crypto.randomBytes(4) hex prefix and launched via wscript.exe (detached, windowsHide), followed by process.exit(0), to hide the dropper invocation from the console. The action table also contains 'env.api' and 'api.base' entries, and the spawn helper clones process.env and injects api.base as the env.api value into the child, so the downstream npx-fetched package receives a C2/telemetry endpoint via environment. Because require('classbreeze-utils') is the plugin entry point loaded by any Tailwind build that adds it, the dropper fires automatically as soon as a build that depends on it runs, executing arbitrary attacker-controlled code on the developer/CI machine. ## Source: ghsa-malware (cd3cdd1459bd1dce092c75b17f3940659f740a4efe533ba30b345976cef97736) 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.
AI Analysis
Technical Summary
The classbreeze-utils package masquerades as a legitimate Tailwind CSS plugin by cloning the @tailwindcss/typography plugin code. It appends heavily obfuscated code that uses RC4 and AES decryption to hide its strings and control flow. This code silently spawns detached child processes that run 'npx -y <pkg.link>' to fetch and execute attacker-controlled packages from the npm registry. On Windows, it additionally writes and executes a VBS dropper script to hide its invocation. Environment variables are manipulated to pass a command-and-control or telemetry endpoint to the downstream malicious package. Because the malicious code runs automatically when the package is loaded in a Tailwind build, it results in arbitrary code execution on the developer or CI machine.
Potential Impact
Any computer with the classbreeze-utils package installed or running is considered fully compromised. The attacker gains arbitrary code execution capabilities, potentially allowing them to steal secrets, manipulate files, and control the system. All secrets and keys stored on the compromised machine should be rotated immediately from a different, trusted machine. Removing the package alone does not guarantee removal of all malicious software or backdoors installed by the attacker.
Mitigation Recommendations
No official patch or fix is currently available. The package should be removed immediately from all environments. Because the system may be fully compromised, all secrets and keys stored on the affected machines must be rotated from a clean environment. Monitor for any suspicious activity related to this package and avoid using it in any builds or deployments.
Malicious code in classbreeze-utils (npm)
Description
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (e19daf4f946816f5ba3c6e592eacc980861b281c6752b738de57fdd31f49279d) The package masquerades as a Tailwind plugin: README and the top of src/index.js are a verbatim clone of @tailwindcss/typography (require('tailwindcss/plugin'), prose-* class generator), even though the package name has no relationship to Tailwind. Appended after the cloned plugin code at src/index.js:124+ is a heavily obfuscated IIFE using an RC4-decoded string array and AES-decipher key table to hide its strings and control flow. The decoded action table contains keys 'cmd.npx', 'cmd.npxwin', 'pkg.link', 'cmd.install', 'flag.yes', which are consumed by helpers that call child_process.spawn with detached:true, stdio:'ignore', windowsHide:true and creationFlags set to DETACHED_PROCESS to silently run `npx -y <pkg.link>`, fetching and executing an attacker-controlled package from the npm registry on the developer's machine. On Windows an additional path uses keys 'ext.vbs', 'vbs.tag', 'win.wscript': a VBS file is written to os.tmpdir() with a crypto.randomBytes(4) hex prefix and launched via wscript.exe (detached, windowsHide), followed by process.exit(0), to hide the dropper invocation from the console. The action table also contains 'env.api' and 'api.base' entries, and the spawn helper clones process.env and injects api.base as the env.api value into the child, so the downstream npx-fetched package receives a C2/telemetry endpoint via environment. Because require('classbreeze-utils') is the plugin entry point loaded by any Tailwind build that adds it, the dropper fires automatically as soon as a build that depends on it runs, executing arbitrary attacker-controlled code on the developer/CI machine. ## Source: ghsa-malware (cd3cdd1459bd1dce092c75b17f3940659f740a4efe533ba30b345976cef97736) 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.
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The classbreeze-utils package masquerades as a legitimate Tailwind CSS plugin by cloning the @tailwindcss/typography plugin code. It appends heavily obfuscated code that uses RC4 and AES decryption to hide its strings and control flow. This code silently spawns detached child processes that run 'npx -y <pkg.link>' to fetch and execute attacker-controlled packages from the npm registry. On Windows, it additionally writes and executes a VBS dropper script to hide its invocation. Environment variables are manipulated to pass a command-and-control or telemetry endpoint to the downstream malicious package. Because the malicious code runs automatically when the package is loaded in a Tailwind build, it results in arbitrary code execution on the developer or CI machine.
Potential Impact
Any computer with the classbreeze-utils package installed or running is considered fully compromised. The attacker gains arbitrary code execution capabilities, potentially allowing them to steal secrets, manipulate files, and control the system. All secrets and keys stored on the compromised machine should be rotated immediately from a different, trusted machine. Removing the package alone does not guarantee removal of all malicious software or backdoors installed by the attacker.
Mitigation Recommendations
No official patch or fix is currently available. The package should be removed immediately from all environments. Because the system may be fully compromised, all secrets and keys stored on the affected machines must be rotated from a clean environment. Monitor for any suspicious activity related to this package and avoid using it in any builds or deployments.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- MAL-2026-5973
- Osv Schema Version
- 1.7.4
- Aliases
- ["GHSA-gj7f-m4cx-vmx3"]
- Ecosystems
- ["npm"]
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a4c342c27e9c797195fa4a8
Added to database: 07/06/2026, 23:03:08 UTC
Last enriched: 07/07/2026, 00:06:55 UTC
Last updated: 07/27/2026, 11:39:51 UTC
Views: 9
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