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GHSA-4rmq-mc2c-r495

Babylon Incorrect FP inactive accounting in costaking creates “phantom stake” that earns rewards after BTC unbond

Also known asGO-2025-4214
Published
Dec 9, 2025
Updated
Dec 15, 2025
Affected
4 pkgs
Patched
1 / 4
Exploits
None indexed

Blast Radius

4 pkgs affected
🐹github.com/babylonlabs-io/babylon/v4🐹github.com/babylonlabs-io/babylon/v3🐹github.com/babylonlabs-io/babylon/v2🐹github.com/babylonlabs-io/babylon

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

A state consistency bug in x/costaking can leave a BTC delegator with non-zero ActiveSatoshis (Phatom Stake) even after they have fully unbonded their BTC delegation, if their Finality Provider (FP) drops out of the active set in the exact same babylon block height. This creates a “phantom stake”: the delegator’s BTC capital is withdrawn, the FP is inactive, but costaking continues to treat the delegation as active BTC stake allowing ongoing rewards accrual without backing BTC.

Impact

An address can keep earning costaking rewards with zero BTC staked.

Reported by @BottyBott.

Affected Packages

4 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/babylonlabs-io/babylon/v4all versions4.2.0
🐹Gogithub.com/babylonlabs-io/babylon/v3all versionsNo fix
🐹Gogithub.com/babylonlabs-io/babylon/v2all versionsNo fix
🐹Gogithub.com/babylonlabs-io/babylonall versionsNo fix

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/babylonlabs-io/babylon/v4. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update github.com/babylonlabs-io/babylon/v4 to 4.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4rmq-mc2c-r495 is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-4rmq-mc2c-r495 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-4rmq-mc2c-r495. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary A state consistency bug in `x/costaking` can leave a BTC delegator with non-zero `ActiveSatoshis` (Phatom Stake) even after they have fully unbonded their BTC delegation, if their Finality Provider (FP) drops out of the active set in the exact same babylon block height. This creates a “phantom stake”: the delegator’s BTC capital is withdrawn, the FP is inactive, but costaking continues to treat the delegation as active BTC stake allowing ongoing rewards accrual without backing BTC. ### Impact An address can keep earning costaking rewards with zero BTC staked. Reported by @Botty
O3 Security · Impact-Aware SCA

Is GHSA-4rmq-mc2c-r495 in your dependencies?

O3 detects GHSA-4rmq-mc2c-r495 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.