dbcve.org
Tss LibApplication · Iofinnet

CVE-2023-26556

CRITICAL · 9.1 CVSS v3.1 Published 2023-04-21
Fix available
A fix is available. Upgrade to 2.0.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.)

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The tss-lib library before version 2.0.0 uses Go's crypto/elliptic package for scalar multiplication in ECDSA key generation (ecdsa/keygen/round_2.go). This implementation contains a timing-sensitive if statement inside a loop, allowing attackers to leak secret key material through timing side-channel analysis. The vulnerability affects io.finnet tss-lib, bnb-chain/tss-lib, and thorchain/tss.

MitigationReplace the non-constant-time scalar multiplication from Go crypto/elliptic with a constant-time implementation (such as crypto/elliptic.P256's constant-time methods or a third-party constant-time library) in all affected code paths including ECDSA key generation round 2.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Tss LibApplication
Affected:< 2.0.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify tss-lib dependency
    Check your go.mod file for any dependency on tss-lib (io.finnet/tss-lib, bnb-chain/tss-lib, or thorchain/tss) and note its version
    Affected if The version listed is below 2.0.0
  2. Locate affected source file
    Search for the file ecdsa/keygen/round_2.go in your project or dependency tree
    Affected if This file exists and uses Go's crypto/elliptic package for scalar multiplication
  3. Check for vulnerable crypto/elliptic usage
    Inspect ecdsa/keygen/round_2.go for imports or usage of crypto/elliptic (such as elliptic.P256() or similar)
    Affected if The code imports or calls crypto/elliptic for ECDSA operations
  4. Verify timing-sensitive code pattern
    Search the round_2.go file for if statements inside loops that operate on secret key material (look for conditional logic on scalar values during multiplication)
    Affected if A timing-sensitive if statement exists inside a loop performing scalar multiplication on secret data

Your environment is affected if you use a tss-lib version below 2.0.0 and your codebase contains the vulnerable ecdsa/keygen/round_2.go file using crypto/elliptic for ECDSA key generation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.0.0 or later
Fixed in 2.0.0
Interim mitigation

Replace the non-constant-time scalar multiplication from Go crypto/elliptic with a constant-time implementation (such as crypto/elliptic.P256's constant-time methods or a third-party constant-time library) in all affected code paths including ECDSA key generation round 2.

Recommended fix High confidence

2.0.0

  1. Check the current version of tss-lib in use by examining go.mod or dependency files
  2. Update the tss-lib dependency to version 2.0.0 or later (e.g., go get github.com/finnetchain/tss-lib/[email protected] or later)
  3. Verify the upgrade by running go mod tidy and go mod verify
  4. Test the upgrade in a non-production environment to ensure compatibility
  5. Deploy the updated version to production

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Tss Lib Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,560
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-26556 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data