CVE-2026-121440

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    CVE-2026-121440

    Published: 3 Nov 2026Last Modified: 5 Nov 2026

    Summary: Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 Forwarded Trailers Header Filter Bypass

    Details: Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/121xxx/CVE-2026-121440.json, https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jxcf-8qw5-5c33, https://nvd.nist.gov/vuln/detail/CVE-2026-121440, https://www.vulncheck.com/advisories/wasmtime-46.0.0-before-48.0.7-and-49.0.0-before-49.0.4-forwarded-trailers-header-filter-bypass

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 423be7a4e4d30bb377c836d317521d1eb874e157
    Fixed -c6846e13f64b07b7912d372db141397058b55f99

    Affected versions

    v49.0.3
    v49.0.2
    v49.0.1
    v49.0.0

    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-2026-121440 | CVE-DB