Summary
Evmos vulnerable to DOS and transaction fee expropiation through Authz exploit
Disclosure
Evmos versions below v11.0.1 do not check for MsgEthereumTx messages that are nested under other messages. This allows a malicious actor to perform EVM transactions that do not meet the checks performed under newEthAnteHandler. This opens the possibility for the DOS of validators and consequently halt the chain through an infinite EVM execution.
Additional details
The attack scenario is as follows:
- The attacker deploys a simple smart contract with an infinite loop to the chain.
- The attacker calls the smart contract using an embedded transaction with an extremely high gas value (
uint64max or similar). - Once the transaction is included in a block, nodes will try to execute the EVM transaction with almost infinite gas and get stuck. This stops new block creation and effectively halts the chain, requiring a manual restart of all nodes.
Users Impacted
All Evmos users are impacted by this vulnerability as it has the potential to halt the chain. Users' funds and chain state are safe but when under attack, the chain could be deemed unusable.
Details
As a temporary workaround, the fix blocks MsgEthereumTxs messages from being sent under the authz module's MsgExec message. It also covers the scenario in which MsgEthereumTx are deeply nested by:
- Doing a recursive check over the nested messages of
MsgExec - Limiting the amount of possible nested messages (inner messages) in
MsgExec
This is done by adding an additional AnteHandler decorator (AuthzLimiterDecorator) for Cosmos and EIP-712 transactions.
This is a state machine-breaking change as it restricts previously allowed messages and thus requires a hard-fork upgrade.
References
Are there any links users can visit to find out more?
For more information
If you have any questions or comments about this advisory:
- Reach out to the Core Team in Discord
- Open a discussion in evmos/evmos
- Email us at [email protected] for security questions
- For Press, email us at [email protected].
Impact
What kind of vulnerability is it? Who is impacted?
An attacker can use this bug to bypass the block gas limit and gas payment completely to perform a full Denial-of-Service against the chain.
GHSA-V6RW-HHGG-WC4X has a CVSS score of 9.1 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (12.0.0); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Has the problem been patched? What versions should users upgrade to?
The vulnerability has been patched on Evmos versions ≥v12.0.0.
Frequently Asked Questions
- What is GHSA-V6RW-HHGG-WC4X? GHSA-V6RW-HHGG-WC4X is a critical-severity security vulnerability in github.com/evmos/evmos/v11 (go), affecting versions < 12.0.0. It is fixed in 12.0.0.
- How severe is GHSA-V6RW-HHGG-WC4X? GHSA-V6RW-HHGG-WC4X has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/evmos/evmos/v11 are affected by GHSA-V6RW-HHGG-WC4X? github.com/evmos/evmos/v11 (go) versions < 12.0.0 is affected.
- Is there a fix for GHSA-V6RW-HHGG-WC4X? Yes. GHSA-V6RW-HHGG-WC4X is fixed in 12.0.0. Upgrade to this version or later.
- Is GHSA-V6RW-HHGG-WC4X exploitable, and should I be worried? Whether GHSA-V6RW-HHGG-WC4X is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-V6RW-HHGG-WC4X is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-V6RW-HHGG-WC4X? Upgrade
github.com/evmos/evmos/v11to 12.0.0 or later.