CVE-2021-21271: Uncontrolled Resource Consumption in Tendermint Core
Summary
CVE-2021-21271: Tendermint Core vulnerable to Uncontrolled Resource Consumption. Affects github.com/tendermint/tendermint versions >= 0.34.0, < 0.34.3. Fixed in 0.34.3. How to fix ↓
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Background
Tendermint Core is an open-source software package written in Go that serves as the core engine for the Tendermint blockchain consensus protocol. It provides a Byzantine Fault Tolerant (BFT) consensus algorithm and is used by various blockchain projects. The vulnerability described in this report affects Tendermint Core versions 0.34.0 to 0.34.2.
Vulnerability Detail
The vulnerability in Tendermint Core versions 0.34.0 to 0.34.2 arises from the handling of evidence of misbehavior. Specifically, the introduction of a new 'Timestamp' field to 'Evidence' structs in version 0.34.0 leads to an issue with inconsistent timestamps for 'DuplicateVoteEvidence' objects. Different nodes in the network may assign different timestamps to these objects, resulting in the formation of invalid evidence. This vulnerability can be exploited to launch denial-of-service attacks on networks running the affected versions of Tendermint Core.
How To Fix
Latest published version: v0.35.9 as of 23 Oct 2026
go get github.com/tendermint/tendermint@v0.35.9Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.34.3
This is the first release that contains the fix.
go get github.com/tendermint/tendermint@v0.34.3Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Conclusion
The vulnerability in Tendermint Core versions 0.34.0 to 0.34.2 can lead to denial-of-service attacks. It is crucial for networks running these versions to upgrade to Tendermint Core version 0.34.3 or later to mitigate the vulnerability. For further support on vulnerability remediation, please contact DevNack.com.
See every vulnerability recorded for github.com/tendermint/tendermint →
FAQ
Tendermint Core is an open-source software package that serves as the core engine for the Tendermint blockchain consensus protocol. It provides a Byzantine Fault Tolerant (BFT) consensus algorithm and is used by various blockchain projects.
The vulnerability affects Tendermint Core versions 0.34.0 to 0.34.2.
This vulnerability can be exploited to launch denial-of-service attacks on networks running the affected versions of Tendermint Core.
To fix this vulnerability, it is recommended to upgrade to Tendermint Core version 0.34.3 or later.
No, there are no workarounds available other than upgrading to a patched version of Tendermint Core.
References
Related vulnerabilities
Recent vulnerabilities recorded for github.com/tendermint/tendermint.
