CVE-2026-32129 — soroban-poseidon
Fix: stellar/rs-soroban-poseidon#10CVE-2026-32129 is a CWE-328 vulnerability in soroban-poseidon. A fix is available for soroban-poseidon — see the affected versions and patch details below.
Poseidon V1 variable-length input collision via implicit zero-padding
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-32129.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
soroban-poseidonReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
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 Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | soroban-poseidon | all versions | 25.0.1cargo update -p soroban-poseidon --precise 25.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for soroban-poseidon, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update soroban-poseidon to 25.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-32129 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-32129 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-32129. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-32129 in your dependencies?
O3 Security finds CVE-2026-32129 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.