CVE-2026-121458

    Dashboard / Vulnerabilities / CVE-2026-121458

    CVE-2026-121458

    Published: 3 Nov 2026Last Modified: 5 Nov 2026

    Summary: Instatic before 0.0.21 Authorization Bypass via MCP Content Read Tools

    Details: Instatic before 0.0.21 contains a missing authorization vulnerability in its AI/MCP content read tools that allows low-privileged authenticated users with ai.chat and content.edit.own capabilities to access data rows belonging to other users by calling content_get_document and content_list_documents without the object-level authorization checks enforced by the normal HTTP API. Attackers can use the MCP interface to retrieve private or unpublished draft content and enumerate rows from the posts system table, resulting in cross-user data disclosure.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/121xxx/CVE-2026-121458.json, https://github.com/CoreBunch/Instatic/security/advisories/GHSA-x5cc-8486-8qqx, https://nvd.nist.gov/vuln/detail/CVE-2026-121458, https://www.vulncheck.com/advisories/instatic-before-authorization-bypass-via-mcp-content-read-tools, https://github.com/CoreBunch/Instatic/releases/tag/v0.0.21, https://github.com/CoreBunch/Instatic

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 1e869573320223b50b912fe86a07aacaca53fd6d
    Fixed -d1abbefacb2e716dcab4c29ca972e2eb32dfab42

    Affected versions

    v0.0.20
    v0.0.19
    v0.0.17
    v0.0.16
    v0.0.15
    v0.0.14
    v0.0.13
    v0.0.12

    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-2026-121458 | CVE-DB