# CVE-2026-32129

## Summary

- **CVE ID:** CVE-2026-32129
- **Severity:** HIGH
- **CVSS Score:** 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N)
- **CWE:** CWE-328
- **Published:** Mar 12, 2026
- **Last Modified:** Mar 16, 2026

## 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.

## Affected Products

- stellar — rs-soroban-poseidon (< 25.0.1)

## References

- [CNA](https://github.com/stellar/rs-soroban-poseidon/security/advisories/GHSA-g2p6-hh5v-7hfm)
- [CNA](https://github.com/stellar/rs-soroban-poseidon/pull/10)
- [CNA](https://github.com/stellar/rs-soroban-poseidon/releases/tag/v25.0.1)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.22%
- **EPSS Percentile:** 12.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._