GHSA-wg2x-rv86-mmpx
SPV Merkle proof malleability allows the maintainer to prove invalid transactions
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
@keep-network/tbtc-v2npmDescription
Summary
By publishing specially crafted transactions on the Bitcoin blockchain, the SPV maintainer can produce seemingly valid SPV proofs for fraudulent transactions.
The issue was originally identified by Least Authority in the tBTC Bridge V2 Security Audit Report as Issue B: Bitcoin SPV Merkle Proofs Can Be Faked. A mitigation was believed to have been in place, but this turned out to contain an error, and the issue had not been effectively mitigated.
Details
This is achieved by creating a 64-byte transaction that the fraudulent transaction treats as a node in its merkle proof:
The attacker creates the malicious transaction E and calculates an unusual but valid transaction D, so that the last 32 bytes of D are a part of the merkle proof of E:
D = foo | hash256(E')
E' = bar | hash256(E)
foo and bar are arbitrary 32-byte values selected to facilitate this attack.
The attacker can then publish D and wait for it to be mined. A valid SPV proof for D can then be transformed into a proof for E by prepending bar and foo to the merkle proof, and changing the transaction index into one matching E's implied position in the merkle tree.
Calculating a suitable value for E' has been estimated to require between 2^60 to 2^81 operations. By contrast, the current Bitcoin hashrate is approximately 2^69. Thus the cost of performing the requisite brute-force is at most similar to, or possibly up to 1,000,000 times lower than, the cost of mining 6 Bitcoin blocks at the current difficulty.
Impact
The vulnerability does not enable the SPV maintainer to do anything they would not have been able to do otherwise. However, the ability to bypass the need to mine 6 blocks at the current difficulty makes abusing the SPV maintainer position significantly cheaper.
Patches
Adding the coinbase transaction and its merkle proof into the SPV proofs prevents this issue, by increasing the brute-force required to 2^224. If the length of the coinbase proof matches the length of the transaction proof, and both proofs are valid for the same header, we can trust that the exploit has not been abused for the transaction.
Workarounds
The trusted SPV maintainer position prevents this issue
References
Weaknesses in Bitcoin’s Merkle Root Construction
Leaf-Node weakness in Bitcoin Merkle Tree Design
SPV proof verification vulnerable to potential (but expensive to exploit) Merkle tree problem #192
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @keep-network/tbtc-v2 | all versions | 1.5.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @keep-network/tbtc-v2. 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.
Fix
Update @keep-network/tbtc-v2 to 1.5.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wg2x-rv86-mmpx is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-wg2x-rv86-mmpx 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-wg2x-rv86-mmpx. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-wg2x-rv86-mmpx in your dependencies?
O3 detects GHSA-wg2x-rv86-mmpx across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.