Summary
Taurus multi-party-sig has OT-based ECDSA protocol implementation flaws
Coinbase researchers reported 2 security issues in our implementation of the oblivious transfer (OT) based protocol DKLS:
1. Secret share recovery attack
If the base OT setup of the protocol is reused for another execution of the OT extension, then a malicious participant can extract a bit of the secret of another participant. By repeating the execution they can eventually recover the whole secret.
Therefore, unlike our comments suggested, you must not reuse an OT setup for multiple protocol executions.
We're adding a warning in the code:
2. Invalid security proof due to incorrect operator
The original 2018 version of the DKLS had a typo in the OT extension protocol when computing the check value in the OT extension: the paper noted a XOR whereas it should be a field multiplication. This erroneous behavior was implemented in our code.
The proof of security fails in this case. No concrete attack is known, however.
The 2023 update of the DKLS paper reported that typo and updated the protocol definition.
As of 20241124, patching is in progress (branch otfix), but not merged to the main branch yes as the tests fail to pass. We're troubleshooting the issue and will merge into the main branch when it's resolved.
As of 20250128, a patched version is available in https://github.com/taurushq-io/multi-party-sig/releases/tag/v0.7.0-alpha-2025-01-28, thanks to https://github.com/taurushq-io/multi-party-sig/pull/119.
Workarounds
Do not reuse an OT setup in the event that an abort is detected, to eliminate the secret recovery attack.
Credits
Thanks to the Coinbase researchers Yi-Hsiu Chen and Samuel Ranellucci for discovering these issues and providing a comprehensive write-up. Thank you to Yehuda Lindell for coordinating the disclosure.
Thanks to Jay Prakash for clarifying the risk of the base setup reuse.
Thanks to @cronokirby for writing the corrected code.
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is GHSA-7F6P-PHW2-8253? GHSA-7F6P-PHW2-8253 is a high-severity security vulnerability in github.com/taurusgroup/multi-party-sig (go), affecting versions <= 0.6.0-alpha-2021-09-21. It is fixed in 0.7.0-alpha-2025-01-28.
- Which versions of github.com/taurusgroup/multi-party-sig are affected by GHSA-7F6P-PHW2-8253? github.com/taurusgroup/multi-party-sig (go) versions <= 0.6.0-alpha-2021-09-21 is affected.
- Is there a fix for GHSA-7F6P-PHW2-8253? Yes. GHSA-7F6P-PHW2-8253 is fixed in 0.7.0-alpha-2025-01-28. Upgrade to this version or later.
- Is GHSA-7F6P-PHW2-8253 exploitable, and should I be worried? Whether GHSA-7F6P-PHW2-8253 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-7F6P-PHW2-8253 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-7F6P-PHW2-8253? Upgrade
github.com/taurusgroup/multi-party-sigto 0.7.0-alpha-2025-01-28 or later.