CVE-2026-86439

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    CVE-2026-86439

    Published: 7 Sept 2026Last Modified: 12 Sept 2026

    Summary: knowns before 0.30.0 Path Traversal via MCP doc and memory tools

    Details: knowns versions before 0.30.0 fail to validate filesystem paths in MCP tool arguments, allowing attackers to read, create, overwrite and delete files outside the project directory. Attackers can supply path arguments containing directory traversal sequences to access arbitrary Markdown files accessible to the server process.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86439.json, https://github.com/knowns-dev/knowns/releases/tag/v0.30.0, https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchp, https://nvd.nist.gov/vuln/detail/CVE-2026-86439, https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools, https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4e, https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129, https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -cead30b2c3a34f66c0c40cb692ed51e588e63bd7

    Affected versions

    v0.29.1
    v0.29.0

    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-2026-86439 | CVE-DB