Summary
Sandbox Breakout in realms-shim
Versions of realms-shim prior to 1.2.0 are vulnerable to a Sandbox Breakout. Reflect.construct can be used on the sandboxed Function constructor to reach the prototypes of the primal Realm, which may allow an attacker to escape the sandbox and execute arbitrary code.
Impact
GHSA-6JG8-7333-554W has a CVSS score of 9.8 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.2.0, 0.6.3); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Upgrade to version 1.2.0 or later.
Frequently Asked Questions
- What is GHSA-6JG8-7333-554W? GHSA-6JG8-7333-554W is a critical-severity security vulnerability in realms-shim (npm), affecting versions < 1.2.0. It is fixed in 1.2.0, 0.6.3.
- How severe is GHSA-6JG8-7333-554W? GHSA-6JG8-7333-554W has a CVSS score of 9.8 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by GHSA-6JG8-7333-554W?
realms-shim(npm) (versions < 1.2.0)ses(npm) (versions < 0.6.3)
- Is there a fix for GHSA-6JG8-7333-554W? Yes. GHSA-6JG8-7333-554W is fixed in 1.2.0, 0.6.3. Upgrade to this version or later.
- Is GHSA-6JG8-7333-554W exploitable, and should I be worried? Whether GHSA-6JG8-7333-554W is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-6JG8-7333-554W is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-6JG8-7333-554W?
- Upgrade
realms-shimto 1.2.0 or later - Upgrade
sesto 0.6.3 or later
- Upgrade