Vulnerability in github.com/tendermint/tendermint (CVE-2021-21271)

Summary

Vulnerability in github.com/tendermint/tendermint (CVE-2021-21271). Risk of unauthorized operations or information disclosure. Exploitable via Timestamp. Mitigation: upgrade to 0.34.3 or later.

Original description

The description as published by the source.

Description

Tendermint Core v0.34.0 introduced a new way of handling evidence of misbehavior. As part of this, we added a new Timestamp field to Evidence structs. This timestamp would be calculated using the same algorithm that is used when a block is created and proposed. (This algorithm relies on the timestamp of the last commit from this specific block.)

In Tendermint Core v0.34.0-v0.34.2, the consensus reactor is responsible for forming DuplicateVoteEvidence whenever double signs are observed. However, the current block is still “in flight” when it is being formed by the consensus reactor. It hasn’t been finalized through network consensus yet. This means that different nodes in the network may observe different “last commits” when assigning a timestamp to DuplicateVoteEvidence.

In turn, different nodes could form DuplicateVoteEvidence objects at the same height but with different timestamps. One DuplicateVoteEvidence object (with one timestamp) will then eventually get finalized in the block, but this means that any DuplicateVoteEvidence with a different timestamp is considered invalid. Any node that formed invalid DuplicateVoteEvidence will continue to propose invalid evidence; its peers may see this, and choose to disconnect from this node. This bug means that double signs are DoS vectors in Tendermint Core v0.34.0-v0.34.2.

Tendermint Core v0.34.3 is a security release which fixes this…

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2021-21271 has been found in github.com/tendermint/tendermint.
Attackers can target a specific entry point like Timestamp over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade github.com/tendermint/tendermint to 0.34.3 or later.
If unsure, ask your IT team or search "github.com/tendermint/tendermint CVE-2021-21271" on the vendor's site.

CVE-2021-21271 (github.com/tendermint/tendermint) — CWE-400
Attack vector: remote (network-reachable) / no user interaction
Attack surface: Timestamp / Evidence / consensus / DuplicateVoteEvidence
Patched: 0.34.3 — apply immediately
Workaround: There are no workarounds, other than upgrading to a patched version of Tendermint Core.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-400) exists in github.com/tendermint/tendermint. Attackers reach the vulnerable code path via Timestamp.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/tendermint/tendermint. Attack surface: Timestamp / Evidence / consensus / DuplicateVoteEvidence.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.34.3.

🛡️ Workaround

Workaround: There are no workarounds, other than upgrading to a patched version of Tendermint Core.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/tendermint/tendermint' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'github.com/tendermint/tendermint' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で github.com/tendermint/tendermint を grep し、稼働しているサービス・バージョンを把握する。
2
Apply temporary workaround mitigate
```
There are no workarounds, other than upgrading to a patched version of Tendermint Core.
```
パッチが適用されるまでの応急処置として、There are no workarounds, other than upgrading to a patched version of Tendermint Core. を実施。回避策の副作用 (機能低下) を確認した上で。
3
Apply patch patch
```
Upgrade github.com/tendermint/tendermint to 0.34.3
```
ステージング環境で 0.34.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
4
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Go github.com/tendermint/tendermint

[{"type":"SEMVER","events":[{"introduced":"0.34.0"},{"fixed":"0.34.3"}]}]

References

advisory nvd.nist.gov
package github.com
web github.com
web github.com
web github.com
web github.com
web pkg.go.dev