GHSA-6jrf-4jv4-r9mw tendermint-rs's Light Client Verifier allows malicious validators to spoof votes from other validators
Malicious validators can spoof votes to bypass light client verification, allowing acceptance of fraudulent blocks in tendermint-rs.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is GHSA-6jrf-4jv4-r9mw?
GHSA-6jrf-4jv4-r9mw is an authentication bypass vulnerability in tendermint-light-client-verifier, published on 9 Apr 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Name: ISA-2025-003: Malicious validator can spoof votes from other validators Component: tendermint-rs Criticality: High (Catastrophic Impact; Rare Likelihood per ACMv1.2) Affected versions: <= v0.40.2 Affected users: Everyone
Description
tendermint-rs contains a critical vulnerability in its light client implementation due to insecure handling of corrupted validator sets. Because it doesn't check that the validator address is correctly derived from the validator's public key when counting votes, it is possible to spoof votes from other validators. The result is being able to construct the malicious block and cheat the light client. The light client will accept such a block, seemingly signed by 2/3+ majority.
Patches
The new tendermint-rs release v0.40.3 fixes this issue.
Unreleased code in the main branch is patched as well.
Workarounds
There are no known workarounds for this issue.
Timeline
- March 12, 2025, 13:41pm PST: Issue reported
- March 12, 2025, 03:00am PST: Core team completes validation of issue
This issue was reported by Felix Wilhelm from Asymmetric Research.
Which versions are affected by GHSA-6jrf-4jv4-r9mw?
2 open source packages ship an affected version, including tendermint-light-client-verifier.
| Package | Affected | Fixed in |
|---|---|---|
tendermint-light-client-verifier crates.io | All versions | 0.40.3 |
tendermint-light-client-verifier crates.io | All versions | 0.40.3 |
How do I fix GHSA-6jrf-4jv4-r9mw?
Upgrade tendermint-light-client-verifier to 0.40.3 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is GHSA-6jrf-4jv4-r9mw being exploited?
There is no known exploitation of GHSA-6jrf-4jv4-r9mw in the wild and no public exploit code.