{"id":"CVE-2026-88899","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 roo…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-73"],"vendor":"knowns-dev","product":"knowns","affected":["knowns < 0.31.0"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-09-11T17:11:17.124340Z"},"published":"2026-09-10","updated":"2026-09-11","sourceUpdated":"2026-09-11T20:33:42.233Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-88899","references":[{"url":"https://github.com/knowns-dev/knowns/security/advisories/GHSA-9h2q-r9fh-f98w","label":"GitHub Security Advisory (GHSA-9h2q-r9fh-f98w)"},{"url":"https://github.com/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go#L1283-L1296"},{"url":"https://github.com/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657"},{"url":"https://github.com/knowns-dev/knowns/releases/tag/v0.31.0","label":"knowns v0.31.0 Release Notes"},{"url":"https://www.vulncheck.com/advisories/knowns-before-0.31.0-external-control-of-agent-working-directory-via-x-opencode-directory-header","label":"VulnCheck Advisory: knowns before 0.31.0 External Control of Agent Working Directory via x-opencode-directory Header"}],"tags":["cve.org","exploit-available"],"epss":0.00438,"epssPercentile":0.3741,"ingestedAt":"2026-09-14T11:11:19.881Z","exploits":{"github":1,"githubRepos":["https://github.com/uziii2208/CVE-2026-88899"],"checkedAt":"2026-09-21T15:31:15.751Z"},"exploitAvailable":true,"slug":"CVE-2026-88899","body":"## Overview\n\nknowns 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.\n\n## Affected\n\n- `knowns < 0.31.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"abyssal","depthScore":66,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":203843,"id":"CVE-2026-88899","ts":1789489256307,"field":"exploit_available","old":"false","new":"true"}]}