CVE-2026-48158

CVE-2026-48158 is a critical-severity vulnerability with a CVSS 4.0 base score of 9.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-506.

Key facts

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.

Frequently asked questions

What is CVE-2026-48158?
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.
How severe is CVE-2026-48158?
CVE-2026-48158 has a CVSS 4.0 base score of 9.3, rated critical severity.
Is CVE-2026-48158 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-48158?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-48158 published?
CVE-2026-48158 was published on 2026-08-10 and last updated on 2026-08-11.

References

Other CWE-506 vulnerabilities

Browse all CWE-506 vulnerabilities →