CVE-2026-48158
Received Received - Intake

Code Execution in use-context-selector React Hook

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: GitHub, Inc.

Description
use-context-selector is a React useContextSelector hook in userland Between 2026-05-18 15:57:18 and 2026-05-19 15:24:34, the default branch contained malicious commits 9d8481a513b7b0d1c0941b220c69b25de748641b through 6f2dae054ca014068bdbbb4db96006424d674124 that executed remote attacker-controlled code on developer machines during `npm install`. The commits were removed by force-push, but local clones, forks, and direct-SHA URLs may still contain them, and `npm install` against an affected checkout will still execute the code today. The package was not published to npm. `src/install.js` was added and wired into the `postinstall` script. It fetched a JavaScript payload from an attacker-controlled HTTPS endpoint (configurable via an environment variable), disabled TLS verification, and evaluated the response as code with `require` available. Execution was deliberately skipped on CI and cloud/serverless environments, targeting developer workstations. The second-stage payload was attacker-hosted and cannot be reconstructed. Assume full compromise of anything reachable from a Node process with the user's permissions. Those who ran `npm install` against an affected checkout on a developer machine on or after 2026-05-18 15:57:18 should treat the machine as compromised, rotate every credential the machine could reach, audit account activity** since 2026-05-18 15:57:18, and clean local clones.

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
CVE-2026-48158
EUVD
EUVD-2026-55661

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-506 The product contains code that appears to be malicious in nature.

Attack-Flow Graph

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Executive Summary

This vulnerability involves a malicious commit in the use-context-selector React library that executed attacker-controlled code during npm install on developer machines. The code fetched and executed a second-stage payload from an attacker-controlled server, targeting developer workstations specifically.

Detection Guidance

Check for suspicious postinstall scripts in package.json files or node_modules directories. Look for recent npm install commands executed on developer machines after 2026-05-18 15:57:18. Inspect environment variables for unexpected HTTPS endpoints or disabled TLS verification settings.

Impact Analysis

If you installed the affected version on a developer machine between 2026-05-18 and 2026-05-19, your machine may be compromised. Attackers could gain full control over anything accessible from the Node process with your permissions.

Mitigation Strategies

Treat any developer machine that ran npm install against an affected checkout after 2026-05-18 15:57:18 as compromised. Rotate all credentials the machine could access, audit account activity since that date, and clean local clones of the repository.

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