| Package | Affected versions | Patched versions |
|---|---|---|
| github.com/cometbft/cometbft | ≥ 0.38.0-alpha.1, < 0.38.21< 0.37.18 | 0.38.210.37.18 |
Name: CSA-2026-001: Tachyon
Criticality: Critical (Catastrophic Impact; Possible Likelihood per ACMv1.2)
Affected versions: All versions of CometBFT
Affected users: Validators and protocols relying on block timestamps
A consensus-level vulnerability was discovered in CometBFT's "BFT Time" implementation due to an inconsistency between how commit signatures are verified and how block time is derived.
This breaks a core BFT Time guarantee: "A faulty process cannot arbitrarily increase the Time value."
Downstream impact on chains affects any module, smart contract, or system that relies on the block timestamp.
The new CometBFT releases v0.38.21 and v0.37.18 fix this issue. The main unreleased branch is also patched.
There are no effective workarounds for this vulnerability. Upgrading to patched versions is required.
This issue was reported to the Cosmos Bug Bounty Program on HackerOne. Credit to SEAL 911 and QED Audit for the discovery and help with the patch.
If you believe you have found a bug in the Cosmos Stack or would like to contribute to the program by reporting a bug, please see https://hackerone.com/cosmos.
If you have questions about Cosmos security efforts, please reach out to our official communication channel at [email protected].
A Github Security Advisory for this issue is available in the CometBFT repository. For more information about CometBFT, see https://docs.cometbft.com/.
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