An integer overflow in nanoid(size) permanently corrupts the process-wide CSPRNG pool, causing all subsequent ID generation to return the deterministic string "uuuuuuuuuuuuuuuuuuuuu". Any application that passes user-influenced values to the size parameter loses all randomness guarantees for session tokens, CSRF tokens, and unique identifiers until process restart.
nanoid (Nano ID) before 5.1.16 contains an infinite loop in the customAlphabet and nanoid functions of its non-secure module (nanoid/non-secure). When these functions are given a negative size, the loop counter is decremented from a negative value and never reaches its termination condition, spinning indefinitely and hanging the calling thread. An application that passes an unvalidated, attacker-controlled negative size to these functions is exposed to a denial-of-service condition.
nanoid (Nano ID) before 5.1.6 contains an infinite loop in the customAlphabet and customRandom functions. When these functions are configured with a size of 0, the internal generation loop never satisfies its exit condition and spins indefinitely, hanging the calling thread. An application that passes an unvalidated, attacker-controlled size of 0 to these functions is exposed to a denial-of-service condition.
When nanoid is called with a fractional value, there were a number of undesirable effects: in browser and non-secure, the code infinite loops on while (size–) in node, the value of poolOffset becomes fractional, causing calls to nanoid to return zeroes until the pool is next filled if the first call in node is a fractional argument, the initial buffer allocation fails with an error Version 3.3.8 and 5.0.9 are …
The package nanoid from 3.0.0, before 3.1.31, are vulnerable to Information Exposure via the valueOf() function which allows to reproduce the last id generated.