ChainBleedv0.1 · open intel
← back to feed·POLYINFRASTRUCTURE2021-10-21 · 4y ago
Incident · SLOWMIST

Polygon Plasma Bridge

Double Spend Attack
Estimated loss
$2.00M
VERDICT —OUT OF SCOPE
Root cause is infrastructure (DNS / cloud / database / third-party API) compromise, not on-chain contract logic. Pre-deployment source review would not surface this; coverage lives in cloud-security + supply-chain audit, separate discipline.
▰ METHOD
INFRASTRUCTURE
INFRASTRUCTURE
Root cause

Root-cause analysis not yet published. The incident description below contains all currently available signal — review the attack transaction directly for definitive forensics.

Forensic narrative

Bug bounty platform Immunefi says white hat hacker Gerhard Wagner submitted a critical vulnerability affecting the Polygon Plasma Bridge on October 5, 2021 that allows attackers to withdraw their burn transactions from the bridge multiple times for up to 223 times. About $850 million is at risk, and an attack with just $100,000 would result in a loss of $22.3 million. Polygon confirmed the bug and immediately began fixing the underlying issue, which was resolved within a week. Polygon agreed to pay up to $2 million for the submission. Attack method (per SlowMist): Double Spend Attack. Reported loss: $ 2,000,000.

Primary source
https://medium.com/immunefi/polygon-double-spend-bug-fix-postmortem-2m-bounty-5a1db09db7f1
Sourced from
slowmist
Technical record
chain
polygon
protocol
Polygon Plasma Bridge
bug_class
infrastructure
date_occurred
2021-10-21
loss_usd
$2,000,000
source_id
sm:polygon-plasma-bridge::2021-10-21
Related — same bug class· infrastructure
2026-04-18
1mo ago
Kelp DAO
Infrastructure-level attack
infrastructure
$293.00M
OUT OF SCOPE
2026-04-18
1mo ago
DNS registrar for eth.limo
DNS hijacking
infrastructure
OUT OF SCOPE
2026-04-04
2mo ago
HypurrFi
Domain Hijacking
infrastructure
OUT OF SCOPE
2026-03-31
2mo ago
Steakhouse Financial
Social Engineering
infrastructure
OUT OF SCOPE
2026-03-19
2mo ago
Neutrl
DNS Hijacking
infrastructure
OUT OF SCOPE
2026-03-18
2mo ago
ETH
Neutrl
DNS Hijacking Attack
infrastructure
OUT OF SCOPE
ChainBleed — live web3 threat intelligence