CVE-2023-26556

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-04-21 · updated 2026-06-17
Weakness: CWE-203

Description

io.finnet tss-lib before 2.0.0 can leak a secret key via a timing side-channel attack because it relies on the scalar-multiplication implementation in Go crypto/elliptic, which is not constant time (there is an if statement in a loop). One leak is in ecdsa/keygen/round_2.go. (bnb-chain/tss-lib and thorchain/tss are also affected.)

Affected products

Iofinnet Tss-Lib: before 2.0.0 — fixed in 2.0.0

How to fix

Upgrade to a fixed version: Iofinnet Tss-Lib 2.0.0. Check the vendor advisory for mitigations.

References

https://github.com/IoFinnet/tss-lib/releases/tag/v2.0.0
https://github.com/bnb-chain/tss-lib/tree/v1.3.5
https://gitlab.com/thorchain/tss/tss-lib/-/tags/v0.1.3
https://medium.com/%40iofinnet/security-disclosure-for-ecdsa-and-eddsa-threshold-signature-schemes-4e969af7155b
https://github.com/IoFinnet/tss-lib/releases/tag/v2.0.0
https://github.com/bnb-chain/tss-lib/tree/v1.3.5
https://gitlab.com/thorchain/tss/tss-lib/-/tags/v0.1.3
https://medium.com/%40iofinnet/security-disclosure-for-ecdsa-and-eddsa-threshold-signature-schemes-4e969af7155b

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