concurrent-ruby is a modern concurrency tools for Ruby. Prior to 1.3.7, Concurrent::AtomicReference#update can enter a permanent busy retry loop when the current value is Float::NAN. The issue is caused by the interaction between AtomicReference#update, which retries until compare_and_set(old_value, new_value) succeeds; Numeric compare_and_set, which checks old == old_value before attempting the underlying atomic swap.; and Ruby NaN semantics, where Float::NAN == Float::NAN is always false. As a result, once an AtomicReference contains Float::NAN, calling #update repeatedly evaluates the callers block and never returns. In services that store externally derived numeric values in an AtomicReference, this can cause CPU exhaustion or permanent request/job hangs. This vulnerability is fixed in 1.3.7.
Weakness
The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Concurrent_ruby | Rubyconcurrency | * | 1.3.7 (excluding) |
| Ruby-concurrent | Ubuntu | questing | * |
| Ruby-concurrent | Ubuntu | upstream | * |