GHSA-9VCR-P3RJ-Q5Q6

Vulnerability from github – Published: 2026-07-09 23:20 – Updated: 2026-07-31 20:17
VLAI
Summary
sigstore-go has a multi-log threshold bypass via single compromised log
Details

Impact

What kind of vulnerability is it? Who is impacted?

A verifier configured with WithTransparencyLog(N>1) or WithSignedCertificateTimestamps(N>1) expected defense-in-depth against the compromise of a single log instance. However, threshold counting counted verified witnesses per-entry or per-validation-path rather than per-log-authority.

As a result, a single compromised transparency log could forge multiple entries with different indices, and a single compromised CT log could verify multiple times (either across multiple certificate chains or via multiple embedded SCTs), fully satisfying the multi-log threshold requirements and defeating the multi-log policy.

Note that this does not affect Cosign, as Cosign sets a threshold of 1.

Patches

Has the problem been patched? What versions should users upgrade to?

Upgrade to v1.1.5.

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

There is no workaround, beyond relying on trusted logs.

Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.1.4"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/sigstore/sigstore-go"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49834"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-345",
      "CWE-347"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-09T23:20:30Z",
    "nvd_published_at": "2026-07-17T20:17:21Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nA verifier configured with WithTransparencyLog(N\u003e1) or WithSignedCertificateTimestamps(N\u003e1) expected defense-in-depth against the compromise of a single log instance. However, threshold counting counted verified witnesses per-entry or per-validation-path rather than per-log-authority.\n\nAs a result, a single compromised transparency log could forge multiple entries with different indices, and a single compromised CT log could verify multiple times (either across multiple certificate chains or via multiple embedded SCTs), fully satisfying the multi-log threshold requirements and defeating the multi-log policy.\n\nNote that this does not affect Cosign, as Cosign sets a threshold of 1.\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nUpgrade to v1.1.5.\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nThere is no workaround, beyond relying on trusted logs.",
  "id": "GHSA-9vcr-p3rj-q5q6",
  "modified": "2026-07-31T20:17:30Z",
  "published": "2026-07-09T23:20:30Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/sigstore-go/security/advisories/GHSA-9vcr-p3rj-q5q6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49834"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/sigstore-go/pull/633"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/sigstore-go/commit/dbb07e62623edd5b175fb9dd5a41dcb85a159207"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sigstore/sigstore-go"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/sigstore-go/releases/tag/v1.2.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "sigstore-go has a multi-log threshold bypass via single compromised log"
}



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