The _freeze function in langgraph’s Task Result Cache includes a parameter called default_cache_key that can be manipulated to force the system to use a weak hash function. This increases the chance of hash collisions, enabling an attacker to overwrite or invalidate cached entries. The vulnerability aligns with CWE‑327 and CWE‑328. Because the default_cache_key is exposed remotely, the flaw can be leveraged from an external attacker.

All installations of langgraph version 1.2.4 or earlier are affected. The defect resides in the libs/langgraph/langgraph/_internal/_cache.py file within the Task Result Cache component. Systems that expose the default_cache_key parameter remain vulnerable until an official fix is released.

The CVSS score of 2.3 indicates low severity, and the EPSS score of <1% suggests a very low probability of exploitation. The exploit is possible remotely but requires crafting inputs that trigger hash collisions, a task described as high complexity and difficult. The vulnerability is not listed in the CISA KEV catalog. Under these conditions, the immediate risk to systems remains modest, though the potential for cache manipulation warrants monitoring and waiting for a patch.