Summary
MikroORM has Prototype Pollution in Utils.merge
A prototype pollution vulnerability exists in the Utils.merge helper used internally by MikroORM when merging object structures.
The function did not prevent special keys such as __proto__, constructor, or prototype, allowing attacker-controlled input to modify the JavaScript object prototype when merged.
Exploitation requires application code to pass untrusted user input into ORM operations that merge object structures, such as entity property assignment or query condition construction.
Prototype pollution may lead to denial of service or unexpected application behavior. In certain scenarios, polluted properties may influence query construction and potentially result in SQL injection depending on application code.
Impact
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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@mikro-orm/core to 6.6.10 or later; @mikro-orm/core to 7.0.6 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-34221? CVE-2026-34221 is a high-severity security vulnerability in @mikro-orm/core (npm), affecting versions < 6.6.10. It is fixed in 6.6.10, 7.0.6.
- Which versions of @mikro-orm/core are affected by CVE-2026-34221? @mikro-orm/core (npm) versions < 6.6.10 is affected.
- Is there a fix for CVE-2026-34221? Yes. CVE-2026-34221 is fixed in 6.6.10, 7.0.6. Upgrade to this version or later.
- Is CVE-2026-34221 exploitable, and should I be worried? Whether CVE-2026-34221 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 CVE-2026-34221 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 CVE-2026-34221?
- Upgrade
@mikro-orm/coreto 6.6.10 or later - Upgrade
@mikro-orm/coreto 7.0.6 or later
- Upgrade