knowns before 0.31.0 External Control of Agent Working Directory via x-opencode-directory Header

{
  "id": "400e0a59842a58a47e9a7ab7f3d09eeed0545d227dee6f84f59ff5cfda30d1c7",
  "url": "https://osv.dev/vulnerability/CVE-2026-88899",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "knowns before 0.31.0 External Control of Agent Working Directory via x-opencode-directory Header",
    "summary": "knowns versions before 0.31.0 fail to properly validate the x-opencode-directory request header in the /api/opencode proxy endpoint. Remote attackers can supply arbitrary directory paths to execute file operations outside the project root on the host system.",
    "evidence": "osv:CVE-2026-88899",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-88899",
      "aliases": [
        "CVE-2026-88899",
        "GHSA-9h2q-r9fh-f98w"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/knowns-dev/knowns",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "193ab83f6dbe1a6d4a0cf63283c57d6a93bea9ef"
                },
                {
                  "fixed": "37db0561b37b48b8bd035a417d7f1da6258ae657"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.31.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "37db0561b37b48b8bd035a417d7f1da6258ae657"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "193ab83f6dbe1a6d4a0cf63283c57d6a93bea9ef"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.31.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.30.0",
            "v0.29.1",
            "v0.29.0",
            "v0.28.0",
            "v0.27.1",
            "v0.27.0",
            "v0.23.0",
            "v0.26.0",
            "v0.25.0",
            "v0.24.1",
            "v0.24.0",
            "v0.22.2",
            "v0.22.1",
            "v0.22.0",
            "v0.21.0",
            "v0.20.5",
            "v0.20.4",
            "v0.20.3",
            "v0.20.2",
            "v0.20.1",
            "v0.20.0",
            "v0.19.2",
            "v0.19.1",
            "v0.19.0",
            "v0.18.4",
            "v0.18.3",
            "v0.18.2",
            "v0.18.1",
            "v0.18.0",
            "v0.17.1",
            "v0.17.0",
            "v0.16.3",
            "v0.16.2",
            "v0.16.1",
            "v0.16.0",
            "v0.15.3",
            "v0.15.2",
            "v0.15.1",
            "v0.15.0",
            "v0.12.4",
            "v0.12.3",
            "v0.12.2",
            "v0.12.1",
            "v0.12.0",
            "v0.11.4",
            "v0.11.3",
            "v0.11.2",
            "v0.11.1",
            "v0.11.0",
            "v0.10.6",
            "v0.10.5",
            "v0.10.4",
            "v0.10.3",
            "v0.10.2",
            "v0.10.1",
            "v0.10.0",
            "v0.9.0",
            "v0.8.9",
            "v0.8.8",
            "v0.8.7",
            "v0.8.6",
            "v0.8.5",
            "v0.8.4",
            "v0.8.3",
            "v0.8.2",
            "v0.8.1",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.0",
            "v0.4.0",
            "v0.3.1",
            "v0.3.0",
            "v0.2.1",
            "v0.2.0",
            "v0.1.8",
            "v0.1.7",
            "v0.1.6",
            "v0.1.5",
            "v0.1.4",
            "v0.1.3",
            "v0.1.2",
            "v0.1.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-88899.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.255203989Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88899.json",
        "https://github.com/knowns-dev/knowns/releases/tag/v0.31.0",
        "https://github.com/knowns-dev/knowns/security/advisories/GHSA-9h2q-r9fh-f98w",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-88899",
        "https://www.vulncheck.com/advisories/knowns-before-0.31.0-external-control-of-agent-working-directory-via-x-opencode-directory-header",
        "https://github.com/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657",
        "https://github.com/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go#L1283-L1296"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-73"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88899.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-88899",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517516,
  "published_at": "2026-09-10T15:28:51.729+00:00"
}