VulnerabilityPublished 12 Mar 2026

CVE-2026-32129: stellar rs-soroban-poseidon · Use of Weak Hash

Affects stellar rs-soroban-poseidonSource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 25.0.1 soon.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score

8.7High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 25.0.1

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

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: High
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the vulnerable system. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the vulnerable system.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 12 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade rs-soroban-poseidon and github/stellar/rs-soroban-poseidon to 25.0.1.

Affected software

Product	Affected	Fixed in
stellarrs-soroban-poseidon	Affected <25.0.1	Fixed in 25.0.1
crates.iogithub/stellar/rs-soroban-poseidon`pkg:cargo/github/stellar/rs-soroban-poseidon`Other threats	Affected <25.0.1	Fixed in 25.0.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Organizations should immediately upgrade the rs-soroban-poseidon library to version 25.0.1 or later, where this vulnerability is addressed. Until upgrading, avoid using Poseidon V1 (PoseidonSponge) for hashing inputs with lengths less than the sponge rate minus one, or implement explicit injective padding to ensure unique input representations. Review all smart contracts and applications using PoseidonSponge to identify and remediate vulnerable hashing calls. Consider migrating to Poseidon2 (Poseidon2Sponge), which is not affected by this issue. Additionally, conduct thorough testing to detect any existing hash collisions that could have been exploited. Incorporate cryptographic best practices by validating input lengths and padding schemes to prevent similar issues. Monitor vendor advisories and threat intelligence feeds for any emerging exploit activity related to this CVE. Finally, educate developers on the importance of using secure cryptographic primitives and staying current with library updates.

Description

CVE-2026-32129 is a high-severity vulnerability in the stellar rs-soroban-poseidon library, specifically affecting the Poseidon V1 (PoseidonSponge) cryptographic hash function used in Soroban smart contracts. The issue arises because PoseidonSponge accepts variable-length inputs without injective padding, implicitly zero-filling unused rate positions when fewer inputs than the sponge rate are provided. This leads to trivial hash collisions where hash([m1, ... , mk]) equals hash([m1, ... , mk, 0]), undermining the hash function's collision resistance. Poseidon2 (Poseidon2Sponge) is not affected. The vulnerability has a CVSS 4.0 score of 8.7, indicating high severity, and does not require authentication or user interaction to exploit. No known exploits are currently reported in the wild.

Impact

This vulnerability undermines the collision resistance of the Poseidon V1 hash function used in Soroban smart contracts, which can have severe consequences for organizations relying on these contracts for secure transactions and data integrity. Attackers could exploit the trivial hash collisions to substitute malicious inputs that produce the same hash as legitimate inputs, potentially enabling fraud, unauthorized asset transfers, or manipulation of contract logic. This compromises the integrity and trustworthiness of blockchain operations using the affected library. Since the vulnerability requires no authentication or user interaction and can be exploited remotely, the attack surface is broad. The impact is particularly critical for financial institutions, decentralized finance (DeFi) platforms, and enterprises leveraging Stellar's Soroban smart contracts for critical business processes. The lack of known exploits in the wild suggests the vulnerability is newly disclosed, but the high CVSS score and fundamental cryptographic weakness indicate urgent remediation is needed to prevent future attacks.

CWE-328Use of Weak Hash (opens in a new tab)
Base weaknessOWASP Top 10 A04:2025: Cryptographic Failures (opens in a new tab)
The product uses an algorithm that produces a digest (output value) that does not meet security expectations for a hash function that allows an adversary to reasonably determine the original input (preimage attack), find another input that can produce the same hash (2nd preimage attack), or find multiple inputs that evaluate to the same hash (birthday attack).
Architecture and Design
Use an adaptive hash function that can be configured to change the amount of computational effort needed to compute the hash, such as the number of iterations ("stretching") or the amount of memory required. Some hash functions perform salting automatically.
OWASP Cheat Sheets
Cryptographic Storage (opens in a new tab)
Key Management (opens in a new tab)
Transport Layer Protection (opens in a new tab)
User Privacy Protection (opens in a new tab)
Password Storage (opens in a new tab)
OWASP ASVS 4.0.3
V2.8.3 (opens in a new tab)
V8.3.7 (opens in a new tab)
V2.9.3 (opens in a new tab)
Attack patterns
Web Services API Signature Forgery Leveraging Hash Function Extension Weakness (opens in a new tab)
Subvert Code-signing Facilities (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 20 Mar 2026, 02:32 UTC

WeaknessesCWE-328

Technical details

References

Community reviews

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