CVE-2024-7884 — Vulnerability in ic_cdk — CVE Details

When a canister method is called via `ic_cdk::call*`, a new Future `CallFuture` is created and can be awaited by the caller to get the execution result. Internally, the state of the Future is tracked and stored in a struct called `CallFutureState`. A bug in the polling implementation of the `CallFuture` allows multiple references to be held for this internal state and not all references were dropped before the `Future` is resolved. Since we have unaccounted references held, a copy of the internal state ended up being persisted in the canister's heap and thus causing a memory leak. ### Impact Canisters built in Rust with `ic_cdk` and `ic_cdk_timers` are affected. If these canisters call a canister method, use timers or heartbeat, they will likely leak a small amount of memory on every such operation. **In the worst case, this could lead to heap memory exhaustion triggered by an attacker.** Motoko based canisters are not affected by the bug. ### Patches The patch has been backported to all minor versions between `>= 0.8.0, <= 0.15.0`. The patched versions available are `0.8.2, 0.9.3, 0.10.1, 0.11.6, 0.12.2, 0.13.5, 0.14.1, 0.15.1` and their previous versions have been yanked. ### Workarounds There are no known workarounds at the moment. Developers are recommended to upgrade their canister as soon as possible to the latest available patched version of `ic_cdk` to avoid running out of Wasm heap memory. > [!NOTE] > Upgrading the canisters (without updating `ic_cdk`) also frees the leaked memory but it's only a temporary solution. ### References - [dfinity/cdk-rs/pull/509](https://github.com/dfinity/cdk-rs/pull/509) - [ic_cdk docs](https://docs.rs/ic-cdk/latest/ic_cdk/) - [Internet Computer Specification](https://internetcomputer.org/docs/current/references/ic-interface-spec)