CVE-2026-88899

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    CVE-2026-88899

    Published: 10 Sept 2026Last Modified: 11 Sept 2026

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

    Details: 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.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88899.json, https://github.com/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go#L1283-L1296, https://github.com/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657, 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

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -193ab83f6dbe1a6d4a0cf63283c57d6a93bea9ef

    Affected versions

    v0.30.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2026-88899 | CVE-DB