CSA-2026-001: Tachyon

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.38.20"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/cometbft/cometbft"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.38.0-alpha.1"
            },
            {
              "fixed": "0.38.21"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.37.17"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/cometbft/cometbft"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.37.18"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-703"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-23T16:56:23Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "# CSA-2026-001: Tachyon\n\n## Description\n\n**Name:** CSA-2026-001: Tachyon\n\n**Criticality:** Critical (Catastrophic Impact; Possible Likelihood per [ACMv1.2](https://github.com/interchainio/security/blob/main/resources/CLASSIFICATION_MATRIX.md))\n\n**Affected versions:** All versions of CometBFT\n\n**Affected users:** Validators and protocols relying on block timestamps\n\n## Description\n\nA consensus-level vulnerability was discovered in CometBFT\u0027s \"BFT Time\" implementation due to an inconsistency between how commit signatures are verified and how block time is derived.\n\nThis breaks a core BFT Time guarantee: \"A faulty process cannot arbitrarily increase the Time value.\"\n\n## Impact\n\nDownstream impact on chains affects any module, smart contract, or system that relies on the block timestamp.\n\n## Patches\n\nThe new CometBFT releases [v0.38.21](https://github.com/cometbft/cometbft/releases/tag/v0.38.21) and [v0.37.18](https://github.com/cometbft/cometbft/releases/tag/v0.37.18) fix this issue. The `main` unreleased branch is also patched.\n\n## Workarounds\n\nThere are no effective workarounds for this vulnerability. Upgrading to patched versions is required.\n\n## Timeline\n\n- January 8, 2026, 5:27PM UTC: Issue reported to Cosmos Bug Bounty Program\n- January 9, 2026, 4:55AM UTC: Issue triaged and validated by core team\n- January 12, 2026, 10:25PM UTC: Core team completes patch for the issue\n- January 13, 2026 4:41PM UTC: Pre-notification delivered to ecosystem partners\n- January 23, 2026, 3:00PM UTC: Patch made available\n\n## Credits\n\nThis issue was reported to the Cosmos Bug Bounty Program on HackerOne. Credit to SEAL 911 and [QED Audit](https://x.com/QED_Audit) for the discovery and help with the patch.\n\nIf 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.\n\nIf you have questions about Cosmos security efforts, please reach out to our official communication channel at security@cosmoslabs.io.\n\nA Github Security Advisory for this issue is available in the CometBFT repository. For more information about CometBFT, see https://docs.cometbft.com/.",
  "id": "GHSA-c32p-wcqj-j677",
  "modified": "2026-01-23T16:56:23Z",
  "published": "2026-01-23T16:56:23Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/cometbft/cometbft/security/advisories/GHSA-c32p-wcqj-j677"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cometbft/cometbft/commit/bf8274fcdbcab2bc652660ae627196a90a6efb97"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/cometbft/cometbft"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cometbft/cometbft/releases/tag/v0.37.18"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cometbft/cometbft/releases/tag/v0.38.21"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "CometBFT has inconsistencies between how commit signatures are verified and how block time is derived"
}