Mantra - Rekt
720,923,967.99 MANTRA left two MANTRA-controlled wallets on Aug. 20, worth roughly $3.6 million at the pre-incident spot price.
94.7% of it reached a single exchange deposit address before MANTRA ever halted the chain; the halt froze only what remained.
MANTRA’s chain remained operationally intact, even as the exploit moved funds through it.
The failure sat one layer down, inside the shared Cosmos EVM stack that MANTRA runs but does not control, the same open-source module relied on by other chains whose teams may not have independently audited every component.
An attacker's contract debited MANTRA's wallets directly, without the private keys, and the stack allowed it to happen.
This was MANTRA's second major crisis in sixteen months, following the insider-dumping collapse that erased roughly $5 billion in April 2025, as detailed in rekt's prior reporting, "Mantra of Misfortune".
This time, the team moved quickly: It halted the chain 14 minutes after the second unauthorized transaction, then patched the network and resumed block production 30 hours and 13 minutes later.
Three more chains would be compromised in the same week by attacks linked to the Cosmos EVM vulnerability cluster.
MANTRA’s own postmortem, published Aug. 28, confirms the root cause: an unsigned-integer underflow in the balance-accounting layer of cosmos/evm, triggered by a specially constructed vesting account and a call through the staking precompile.
As of that publication, none of the extracted funds had been recovered.
The bug is confirmed. The halt worked as a containment mechanism, but only for what remained. Eight days later, why hasn’t a single token come back?
MANTRA broke the news itself.
On Aug. 20, the team posted only that it was "aware of an incident," had frozen the chain as a precaution, and had no root cause or timeline to share.
No amount, no addresses, no name for what had gone wrong.
Roughly nine and a half hours later, a second post narrowed things slightly: The incident was isolated to the Cosmos EVM module, two MANTRA-managed wallets were affected, and no user funds had been touched.
Still nothing on how much.
The accounting came from somewhere else, at first.
Rarma traced the drain to two sources: 600,000,035.55 MANTRA from the null/burn address and 120,923,932.44 MANTRA from a genesis-era multisig.
The funds moved through a single attacker wallet, which fired 24 transactions before going quiet.
Rarma reported zero realized value, because nothing had yet left the chain to be sold.
MANTRA's own postmortem, published Aug. 28, put a different figure on it: Roughly $3.6 million, at the pre-incident spot price of $0.005 per token.
It took MANTRA eight days to publicly confirm the amount and mechanism that Rarma had pieced together from public transactions within hours.
What was worth protecting in that gap?
One Day Too Late
The confirmed root cause begins in May.
On May 13, Cosmos Labs opened pull request #1176, titled “fix: harden statedb balance and event amount handling.” Its description said the change would “guard StateDB balance subtraction against underflow” and make precompile balance-event parsing denomination-aware.
The pull request merged into the main branch on May 15.
An independent researcher published a full write-up of the underlying exploit path on July 27, in a piece titled "Printing Infinite Money on the Cosmos Blockchain," reportedly after first reporting it through HackerOne.
The backport to the release branches did not begin until Aug. 13.
PR #1253 and PR #1254 were both merged into their respective release branches on Aug. 19, the same day Cosmos Labs shipped v0.7.2, whose release notes described the update as containing “important security fixes” and recommended a “coordinated upgrade.”
There was no CVE, no advisory number, and nothing indicating that the fix addressed a live exploit path.
MANTRA's chain went dark the next day.
That is the story the rest of the cluster tells.
MANTRA's own postmortem, published Aug. 28, confirms the same account: An unsigned-integer underflow in the balance-accounting layer of cosmos/evm, triggered by a specially constructed vesting account combined with a call through the staking precompile.
It was the defect the May guard was written to catch.
A competing account had pointed backward instead, to January, when an ICS20 precompile flaw drained roughly $7 million from Saga's EVM network.
Cosmos Labs documented the bug as ASA-2026-002, shipped a permanent fix in v0.6.0 by March, and named MANTRA among the 15 chains it contacted to coordinate remediation.
But that was not the mechanism MANTRA ultimately identified.
Its Aug. 28 postmortem does not mention ICS20. Instead, it describes an unsigned-integer underflow in the cosmos/evm balance-accounting layer, triggered by a specially constructed vesting account and a call through the staking precompile.
MANTRA's postmortem lays out the mechanism transaction by transaction.
An attacker-controlled address submitted a CreateVestingAccount message at block 17,444,907 at 19:04:50 UTC on Aug. 20.
Seventy seconds later, a transaction in block 17,444,928 moved 600,000,035.56 MANTRA out of the null/burn address and into the attacker's wallet.
A nearly identical sequence followed at 22:58:47 UTC: A second CreateVestingAccount message, then, fourteen seconds later, a transaction in block 17,449,159 draining 120,923,932.44 MANTRA from the genesis-era multisig.
Vesting accounts, it turns out, weren't a competing theory. They were the mechanism, confirmed in MANTRA's own account.
The bug is no longer a mystery. A guard against it existed three months before MANTRA needed it, but the fix did not reach the relevant release branch, or the affected chains, in time.
Was the failure in the code, or in the release schedule that sat on the fix?
Mostly Gone
The attacker sent 24 transactions during the incident, draining two compromised addresses.
MANTRA halted the chain at block 17,449,398.
Almost all of the extracted funds reached an exchange-deposit address on MANTRA Chain before the halt caught up.
Attacker's Wallet: mantra13n9sk3p8x7tpq9adgxvzv9q0qev953mld0hwva
The market punished the token anyway. MANTRA fell 18.5% in the hours around the halt, from $0.005060 to a record low of $0.004126, while trading volume spiked nearly 600% as holders reacted to a chain going dark without an explanation attached.
MANTRA restarted on Aug. 22 running patched v8.4.0. There was no rollback, no alteration of the recorded chain state, and user balances were left exactly as they stood before the halt began.
As of Aug. 28, none of it, the frozen 5.27% included, had been recovered.
The funds never crossed a bridge or left MANTRA Chain for another network.
But “on-chain” and “untouched” turned out to be two different claims. Almost all of the extracted funds reached an exchange-deposit address on MANTRA Chain before the halt caught up.
Three more chains running the same underlying stack would not be so fortunate that week.
So what, exactly, separated a contained incident from a catastrophic one?
Everyone Else's Turn
MANTRA's halt bought it time, but not an untouched ledger, most of the drained funds had already reached an exchange before the chain went dark.
Two days later, TAC and KiiChain got neither.
On Aug. 22, the same vulnerability cluster drained 2,985,651,403 TAC from a single account and 148,326,583.15 KII across 18 repeated withdrawals from KiiChain.
Rarma’s forensic thread links TAC’s exploit to the same vesting-account and staking-precompile pattern later confirmed by MANTRA.
TAC has not independently confirmed that mechanism, so the comparison remains an external attribution.
The incidents nevertheless ended very differently: MANTRA’s funds moved to an exchange-deposit address before the halt.
TAC’s stolen tokens and most of KiiChain’s stolen KII crossed bridges to other networks.
TAC's attacker bridged the tokens to BNB Chain in 95 seconds, roughly four hours before TAC's own halt took effect.
KiiChain froze 54.4% of the stolen KII on-chain; most of the remainder was bridged out and sold for roughly 1.61 million BUSD.
Nesa followed two days later. The project said it had identified “malicious behavior” on its L1 exploiting a Cosmos EVM vulnerability and had taken “swift action” to stem the impact.
Services would return only after Nesa applied a software fix and additional remedies to ensure safe operation. The project also said it had notified all exchanges and that deposits would resume once the work was complete.
With Nesa’s endpoints still returning 503 errors, Rarma reconstructed the cross-chain movement from Ethereum-side Hyperlane logs.
The evidence now pointed to a broader ecosystem failure: Multiple chains had been hit by the same Cosmos EVM vulnerability, some had halted too late to contain the funds, and the public response from the module’s maintainers was only beginning.
Cosmos Labs first acknowledged an "ongoing security incident" on Aug. 24, four days after MANTRA's halt and two days after TAC and KiiChain were compromised.
On Aug. 25, it recommended that public chains running Cosmos EVM versions earlier than v0.6.2 on the v0.6 branch or v0.7.2 on the v0.7 branch halt immediately and upgrade to patched releases, six days after the public release of v0.7.2, which included the underflow fix.
KiiChain's postmortem, published Aug. 23, called the losses "avoidable" and directly criticized Cosmos Labs' disclosure process.
It argued that every Cosmos EVM chain with vesting accounts enabled carried the same exposure, which it said explained why MANTRA and TAC were compromised in the same week.
Publishing a fix publicly before privately warning the chains running it, KiiChain wrote, "hands the vulnerability to anyone reading the commit."
KiiChain was not alone in that assessment.
Indie Developer De called the disclosure "negligent AF," pointing to the Aug. 19 release: “This release contains important security fixes. All chains should upgrade ASAP using a coordinated upgrade.”
The release included no public advisory and no main-channel announcement; the GitHub release itself described the change only as containing “important security fixes” and urged chains to upgrade using a coordinated upgrade.
Protos likewise reported that MANTRA, TAC, KiiChain, and Nesa all appeared to be affected by the same Cosmos EVM vulnerability.
MANTRA, for its part, was already carrying weight before any of this began.
This is the same token that lost 90% of its value in April 2025, and the exploit landed amid Inveniam Capital Partners' proposed acquisition of MANTRA, a deal still targeted to close in the third quarter.
Four chains, one vulnerability cluster and a disclosure timeline nobody has fully explained.
So who, exactly, gets to call this contained?
MANTRA wasn't beaten by a hacker's ingenuity. It was beaten by an ecosystem that still doesn't treat disclosure as part of the fix.
Saga lost roughly $7 million to a Cosmos EVM bug in January.
Cosmos Labs shipped a permanent fix in March and marked the advisory as resolved.
Seven months later, a compiled timeline placed the same shared module at the center of attacks affecting four more chains over five days.
MANTRA's own postmortem, published Aug. 28, confirmed which bug hit it: The same underflow the May guard was written to catch.
By the numbers, 720,923,967.99 MANTRA, roughly $3.6 million by MANTRA's own postmortem valuation, was extracted from two wallets.
MANTRA reported no user funds exploited. No stolen tokens crossed a bridge to another blockchain, though 94.7% of them did reach an exchange deposit address before the halt caught up, and the network restarted roughly 30 hours after the halt.
But clean is not the same as accountable.
A team fast enough to halt the chain and preserve the remaining funds during an active drain has had over a week to confirm the bug that caused it, and did, but as of that confirmation, none of the extracted MANTRA, frozen or otherwise, had actually been recovered.
Shared infrastructure holds only when someone treats a warning as urgently as the code underneath it. Nobody in this stack has proven that yet.
A chain can survive an exploit intact, confirm the exact bug that caused it, and still recover nothing for the people it happened to.
Eight days later, what exactly does "contained" mean if nothing comes back?
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