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🛡️ GHSA-6jrf-4jv4-r9mw — tendermint-light-client-verifier

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-863 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

tendermint-rs's Light Client Verifier allows malicious validators to spoof votes from other validators

Name: ISA-2025-003: Malicious validator can spoof votes from other validators

Component: tendermint-rs

Criticality: High (Catastrophic Impact; Rare Likelihood per [ACMv1.2](https://github.com/interchainio/security/blob/main/resources/CLASSIFICATION_MATRIX.md))

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](https://github.com/informalsystems/tendermint-rs/releases/tag/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](https://www.asymmetric.re/).

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. Rated impact: confidentiality none, integrity high, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Attack requirements: None — no deployment-specific condition has to hold.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Confidentiality impact: None.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: None.

Weakness class

GHSA-6jrf-4jv4-r9mw is classified as CWE-863: Incorrect Authorization. An authorisation check runs but reaches the wrong conclusion, permitting actions it should refuse.

Affected software

GHSA-6jrf-4jv4-r9mw is recorded against 1 package.

  • tendermint-light-client-verifier

Timeline and source

Published on 9 April 2025. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

github.com (Web)
github.com (Web)
github.com (Package)

Other advisories for this package

tendermint-light-client-verifier has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-863: Incorrect Authorization) in other software:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CWE CWE-863
Public Exploit ✅ No
Source OSV
Published 2025-04-09
Updated 2026-08-20
Modified 2025-04-09
Fix URL N/A

Affected Packages

Software From version Fixed in
tendermint-light-client-verifier — —

Similar Threats

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