Malicious code in express-session-kit (npm)
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (076f813c0d0a60ee43f7a73f8aad609e5043cd8d92b57b5c3c3c08954accbb4f) The package impersonates the popular express-session library by copying its name pattern, author metadata (TJ Holowaychuk <[email protected]>), and repository field (expressjs/session-kit). The library body is a verbatim copy of express-session with a dropper appended to index.js: an initServer() function invoked at module load spawns a detached, stdio-ignored `node` subprocess to run a sibling payload script. That payload (session/check.js) performs an HTTP GET to http://check-server-state.vercel.app/server/v2 with a `bearrtoken: gemini` header, and when the endpoint responds with HTTP 404 carrying a JSON `token` field, wraps that field with `new Function("require", err.response.data.token)` and immediately invokes it with the real require — granting the remote endpoint arbitrary code execution in the Node process. Delivery via a 404 error body is a covert channel designed to look like a benign failed probe. Although the current dropper references./lib/check.js while the payload actually ships at./session/check.js and the spawn/path bindings are not imported (so the current tarball's dropper would throw before spawning), the second-stage payload file is present, complete, and directly requireable; any consumer that requires the payload — or a trivial fix in a subsequent version — makes the RCE live. Combined with the typosquat cover, this is a supply-chain attack targeting developers who mistype express-session. ## Source: ghsa-malware (44b1bb99fbd84a5cd6a12254371c4689b14a2b8f679157961cd58e26b87b26f9) 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 express-session-kit package mimics the express-session library by copying its name pattern, author metadata, and repository fields. It includes a dropper function that spawns a detached Node.js subprocess to run a payload script. This payload performs an HTTP GET request to a remote server endpoint, expecting a 404 response containing a JSON token. The token is then wrapped in a new Function call and executed with the real require function, enabling arbitrary code execution in the Node.js environment. Although the current dropper has a path typo that prevents immediate execution, the payload script is present and directly requireable, meaning any consumer requiring it or a trivial fix in future versions would activate the RCE. This is a deliberate supply-chain attack exploiting typosquatting to compromise developer environments.
Potential Impact
Any system that installs or runs the express-session-kit package is at risk of full compromise due to remote code execution capabilities. Attackers can execute arbitrary code within the Node.js process, potentially leading to theft of secrets, keys, and full system control. The presence of this package on a system indicates a high likelihood of compromise, and all sensitive credentials on the affected system should be considered exposed and rotated immediately. Removing the package alone may not fully remediate the compromise as attackers may have already installed additional malicious software.
Mitigation Recommendations
No official patch or fix is available since this is a malicious package rather than a vulnerability in legitimate software. The recommended mitigation is to immediately remove the express-session-kit package from all systems. All secrets and keys stored on affected systems should be rotated from a separate, trusted environment. Developers should verify package names carefully to avoid typosquatting attacks and rely on official package sources. Monitor for any suspicious activity indicating persistent compromise beyond the package removal.
Malicious code in express-session-kit (npm)
Description
--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (076f813c0d0a60ee43f7a73f8aad609e5043cd8d92b57b5c3c3c08954accbb4f) The package impersonates the popular express-session library by copying its name pattern, author metadata (TJ Holowaychuk <[email protected]>), and repository field (expressjs/session-kit). The library body is a verbatim copy of express-session with a dropper appended to index.js: an initServer() function invoked at module load spawns a detached, stdio-ignored `node` subprocess to run a sibling payload script. That payload (session/check.js) performs an HTTP GET to http://check-server-state.vercel.app/server/v2 with a `bearrtoken: gemini` header, and when the endpoint responds with HTTP 404 carrying a JSON `token` field, wraps that field with `new Function("require", err.response.data.token)` and immediately invokes it with the real require — granting the remote endpoint arbitrary code execution in the Node process. Delivery via a 404 error body is a covert channel designed to look like a benign failed probe. Although the current dropper references./lib/check.js while the payload actually ships at./session/check.js and the spawn/path bindings are not imported (so the current tarball's dropper would throw before spawning), the second-stage payload file is present, complete, and directly requireable; any consumer that requires the payload — or a trivial fix in a subsequent version — makes the RCE live. Combined with the typosquat cover, this is a supply-chain attack targeting developers who mistype express-session. ## Source: ghsa-malware (44b1bb99fbd84a5cd6a12254371c4689b14a2b8f679157961cd58e26b87b26f9) 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 express-session-kit package mimics the express-session library by copying its name pattern, author metadata, and repository fields. It includes a dropper function that spawns a detached Node.js subprocess to run a payload script. This payload performs an HTTP GET request to a remote server endpoint, expecting a 404 response containing a JSON token. The token is then wrapped in a new Function call and executed with the real require function, enabling arbitrary code execution in the Node.js environment. Although the current dropper has a path typo that prevents immediate execution, the payload script is present and directly requireable, meaning any consumer requiring it or a trivial fix in future versions would activate the RCE. This is a deliberate supply-chain attack exploiting typosquatting to compromise developer environments.
Potential Impact
Any system that installs or runs the express-session-kit package is at risk of full compromise due to remote code execution capabilities. Attackers can execute arbitrary code within the Node.js process, potentially leading to theft of secrets, keys, and full system control. The presence of this package on a system indicates a high likelihood of compromise, and all sensitive credentials on the affected system should be considered exposed and rotated immediately. Removing the package alone may not fully remediate the compromise as attackers may have already installed additional malicious software.
Mitigation Recommendations
No official patch or fix is available since this is a malicious package rather than a vulnerability in legitimate software. The recommended mitigation is to immediately remove the express-session-kit package from all systems. All secrets and keys stored on affected systems should be rotated from a separate, trusted environment. Developers should verify package names carefully to avoid typosquatting attacks and rely on official package sources. Monitor for any suspicious activity indicating persistent compromise beyond the package removal.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- MAL-2026-10131
- Osv Schema Version
- 1.7.4
- Aliases
- ["GHSA-v8j2-pw9x-xx7p"]
- Ecosystems
- ["npm"]
- Database Specific Severity
- null
- Cvss Version
- null
Threat ID: 6a520ecc68715ace438f641d
Added to database: 07/11/2026, 09:37:16 UTC
Last enriched: 07/11/2026, 09:59:01 UTC
Last updated: 07/26/2026, 16:56:27 UTC
Views: 31
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