CVE-2026-26267 is a vulnerability in the Stellar rs-soroban-sdk, a Rust SDK used for developing Soroban smart contracts. The root cause lies in the #[contractimpl] procedural macro, which generates code to wire up contract function calls. Prior to patched versions (22.0.10, 23.5.2, 25.1.1), the macro incorrectly generates calls using the syntax MyContract::value() even when processing trait implementations. When a contract defines both an inherent implementation (impl MyContract) and a trait implementation (impl Trait for MyContract) with identically named functions, the macro-generated code calls the inherent function instead of the trait function. This is problematic because trait functions often include essential security checks, such as verifying caller authorization, which the inherent functions may omit. As a result, the Wasm-exported entry point silently invokes the wrong function, bypassing security controls without any explicit error or warning. The fix changes the macro to generate calls using fully qualified syntax (<Type as Trait>::func()), ensuring Rust resolves to the trait method regardless of inherent functions with the same name. This vulnerability affects all versions before 22.0.10, 23.5.2, and 25.1.1, impacting contracts compiled with these SDK versions. Exploitation requires no privileges or user interaction, making it a critical integrity risk for deployed smart contracts on the Stellar blockchain. Developers must upgrade the soroban-sdk-macros package and recompile contracts or avoid naming conflicts between inherent and trait functions to mitigate this issue.

This vulnerability undermines the integrity of Soroban smart contracts by causing them to execute unintended code paths that bypass critical security checks. Specifically, if the trait implementation includes authorization or validation logic that the inherent function lacks, attackers can interact with the contract's public interface to invoke insecure functions, potentially leading to unauthorized actions such as fund transfers or state changes. Since the vulnerability affects the core SDK used to build contracts on the Stellar blockchain, any contract compiled with vulnerable versions is at risk. This could erode trust in the affected contracts and the broader Stellar ecosystem. The vulnerability does not directly impact confidentiality or availability but poses a high risk to contract integrity and authorization enforcement. Given the ease of exploitation (no privileges or user interaction required) and the silent nature of the failure, attackers could exploit this flaw without detection. Organizations relying on Soroban smart contracts for financial or critical operations face significant risk of unauthorized transactions or logic bypasses until patched.

1. Upgrade the soroban-sdk-macros package to version 22.0.10, 23.5.2, or 25.1.1 or later, and recompile all Soroban contracts to ensure the macro generates correct trait function calls. 2. If immediate upgrading is not feasible, audit all contracts for naming conflicts between inherent functions and trait functions; rename or remove any inherent functions that share names with trait functions to prevent ambiguous resolution. 3. Implement thorough code reviews focusing on function naming and macro usage to avoid similar issues in future contract development. 4. Employ automated static analysis tools to detect conflicting function names in contract codebases. 5. Monitor deployed contracts for anomalous behavior that could indicate exploitation of this vulnerability. 6. Educate developers on the importance of understanding Rust trait vs inherent function resolution semantics, especially in macro-generated code. 7. Consider adding runtime checks or additional authorization layers outside the vulnerable macro-generated code as a defense-in-depth measure until all contracts are patched.