Vulnerability Description
soroban-poseidon provides Poseidon and Poseidon2 cryptographic hash functions for Soroban smart contracts. Poseidon V1 (PoseidonSponge) accepts variable-length inputs without injective padding. When a caller provides fewer inputs than the sponge rate (inputs.len() < T - 1), unused rate positions are implicitly zero-filled. This allows trivial hash collisions: for any input vector [m1, ..., mk] hashed with a sponge of rate > k, hash([m1, ..., mk]) equals hash([m1, ..., mk, 0]) because both produce identical pre-permutation states. This affects any use of PoseidonSponge or poseidon_hash where the number of inputs is less than T - 1 (e.g., hashing 1 input with T=3). Poseidon2 (Poseidon2Sponge) is not affected.
Related Weaknesses (CWE)
References
- https://github.com/stellar/rs-soroban-poseidon/pull/10
- https://github.com/stellar/rs-soroban-poseidon/releases/tag/v25.0.1
- https://github.com/stellar/rs-soroban-poseidon/security/advisories/GHSA-g2p6-hh5
FAQ
What is CVE-2026-32129?
CVE-2026-32129 is a documented vulnerability. soroban-poseidon provides Poseidon and Poseidon2 cryptographic hash functions for Soroban smart contracts. Poseidon V1 (PoseidonSponge) accepts variable-length inputs without injective padding. When a...
How severe is CVE-2026-32129?
CVSS scoring is not yet available for CVE-2026-32129. Check NVD for updates.
Is there a patch for CVE-2026-32129?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.