Description

Overview

P2PKH has 20 bytes just like P2SH. We protect against revealing P2PKH deposits by manually assembling the expected P2SH script in the smart contract and comparing hashes. However, we missed the case when the attacker embeds a valid P2SH inside of P2PKH as an output script. bitcoin-spv library extracts the P2SH from P2PKH and we treat it as a valid P2SH output.

This does not lead to stealing funds but can lead to protocol insolvency.

The off-chain client handles this case correctly, but the problem is in the optimistic minting bot. The bot assumes that if the funding TX exists on Bitcoin with the right amount and it was successfully revealed, the transaction is valid.

https://bugs.immunefi.com/magnus/672/projects/502/bug-bounty/reports/55982

Steps

Since there is a 24-hour governance delay on upgrading the Bridge smart contract, we are going to pause optimistic minting.

Pause optimistic minting.
Deploy new Bridge implementation with Deposit library containing a fix, WITHOUT VERIFYING THE CODE on Etherscan.
Schedule upgrade transaction.
After 24 hours, finalize upgrade.
Unpause optimistic minting.

Basic information

Type: reviewed
Severity: high
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2026-03-02 22:09:19 UTC
Updated: 2026-03-02 22:09:20 UTC
GitHub reviewed: 2026-03-02 22:09:19 UTC

CVSS Scores

Base score	Version	Severity	Vector
7.5	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.

Identifiers

Type	Value
GHSA	GHSA-8986-v76q-8vr2 ↗

CWEs

CWE id	Name
CWE-328	Use of Weak Hash

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
npm	@keep-network/tbtc-v2	<= 1.8.1	1.8.2	—

@keep-network/tbtc-v2 revealing P2PKH deposit with a wrapped P2SH script