CVE-2026-86205

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    CVE-2026-86205

    Published: 6 Sept 2026Last Modified: 10 Sept 2026

    Summary: h3 before 2.0.1-rc.18 Open Redirect via redirectBack()

    Details: h3 versions before 2.0.1-rc.18 contain an open redirect vulnerability in the redirectBack() utility that fails to sanitize protocol-relative paths in the Referer header pathname. Attackers can craft a same-origin URL with a double-slash path segment that passes origin validation but produces a Location header interpreted by browsers as a protocol-relative redirect to an external domain.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86205.json, https://github.com/h3js/h3/security/advisories/GHSA-fp4x-ggrf-wmc6, https://nvd.nist.gov/vuln/detail/CVE-2026-86205, https://www.vulncheck.com/advisories/h3-before-2.0.1-rc.18-open-redirect-via-redirectback

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 388b8f06e060a219d11bbc6be7f70f38d8bbea01
    Fixed -cb70e1ba513be827bb3698127bb7d06467412911

    Affected versions

    v2.0.1-rc.17

    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-2026-86205 | CVE-DB