EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
github.com/tharsis/evmosReal-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
Impact
What kind of vulnerability is it? Who is impacted?
Classification
The vulnerability has been classified as critical with a score of 9.0 (highest). It has the potential to affect and drain unclaimed airdrop funds from Cosmos and Osmosis eligible user addresses.
Disclosure
The attack requires advanced knowledge of the internals of the core and application packages of IBC, IBC relayers, the Cosmos SDK AnteHandler, and the Evmos x/claims module. The step-by-step attack is described below:
- An actor creates a malicious chain with a custom
AnteHandlerthat skips signature verification for transactions, specifically IBCMsgTransfer. This allows the attacker to impersonate any account by setting a customsenderaddress field of the IBC transfer message. - The malicious actor then connects this newly created chain via IBC to Evmos and fills the
recipientaddress from the transfer message with an address they control. - Once the IBC packet containing the Transfer data is relayed to Evmos, it is processed by the claims module IBC middleware. Which migrates the claim records to the recipient address, which is owned by the attacker.
- The attacker then performs two airdrop Actions, claiming up to 75% of the total initial claimable amount.
- The Actor repeats steps 1., 2., and 3. for every address that has unclaimed funds from the airdrop. This automatically claims 75% of the unclaimable amount.
- The malicious actor performs the final Action, claiming 100% of all the user funds.
- Then, the attacker transfers the funds to another chain with a DEX (Osmosis, Cosmos Hub) via IBC.
- Finally, the attacker withdraws the total amount in fiat through a centralized exchange.
Users impacted
No users have suffered the loss of funds as no malicious chains have been connected to Evmos.
Patches
Has the problem been patched? What versions should users upgrade to?
The patch involves defining a list of authorized channels for chains that are connected to Evmos via IBC. This restricts the chains that have the capability of migrating users' claims records as per the specification. By default, the authorized destination channels are "channel-0" (Osmosis) and "channel-3" (Cosmos Hub).
Please upgrade your mainnet node and validator to v2.0.1 ASAP.
Workarounds
Is there a way for users to fix or remediate the vulnerability without upgrading?
No, the fix for the critical vulnerability is state machine breaking. An upgrade procedure must be coordinated with the nodes running the network.
References
Are there any links users can visit to find out more?
- Claims module spec: evmos.dev/modules/claims
- Cosmos SDK documentation: docs.cosmos.network
- IBC documentation: ibc.cosmos.network
For more information
If you have any questions or comments about this advisory:
- Reach out to the Core Team in Discord
- Open an issue in tharsis/evmos
- Email us at [email protected]
Thanks to the Core IBC team at Interchain GmbH for the secure disclosure of this vulnerability
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/tharsis/evmos | all versions | 2.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/tharsis/evmos. 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 github.com/tharsis/evmos to 2.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5jgq-x857-p8xw 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-5jgq-x857-p8xw 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-5jgq-x857-p8xw. 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-5jgq-x857-p8xw in your dependencies?
O3 detects GHSA-5jgq-x857-p8xw across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.