CVE-2026-48161

CVE-2026-48161 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

react18-use is a React 19 use hook shim. Between 2026-05-19 01:07:01 and 2026-05-19 15:20:43, the default branch contained malicious commits 7b79148d1495a2505f9277da295a98cf176f4496 through 7b79148d1495a2505f9277da295a98cf176f4496 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 2026-05-19 01:07:01 should treat the machine as compromised, rotate every credential the machine could reach, audit account activity since 2026-05-19 01:07:01, and clean local clones.

Frequently asked questions

What is CVE-2026-48161?
react18-use is a React 19 use hook shim. Between 2026-05-19 01:07:01 and 2026-05-19 15:20:43, the default branch contained malicious commits 7b79148d1495a2505f9277da295a98cf176f4496 through 7b79148d1495a2505f9277da295a98cf176f4496 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 2026-05-19 01:07:01 should treat the machine as compromised, rotate every credential the machine could reach, audit account activity since 2026-05-19 01:07:01, and clean local clones.
How severe is CVE-2026-48161?
CVE-2026-48161 has a CVSS 4.0 base score of 9.3, rated critical severity.
Is CVE-2026-48161 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (35th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-48161?
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-2026-48161 published?
CVE-2026-48161 was published on 2026-08-10 and last updated on 2026-08-11.

References

Other CWE-506 vulnerabilities

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