CVE-2026-121439

    Dashboard / Vulnerabilities / CVE-2026-121439

    CVE-2026-121439

    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 HTTP Response Splitting via wasi-http

    Details: Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 contains a response splitting vulnerability in wasi-http p3 that allows guests to set unvalidated content-length headers. Malicious wasip3 guests can splice an existing body into a new response with an incorrect content-length to perform response splitting or injection attacks.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/121xxx/CVE-2026-121439.json, https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-9prg-84vf-g5fc, https://nvd.nist.gov/vuln/detail/CVE-2026-121439, https://www.vulncheck.com/advisories/wasmtime-46.0.0-before-48.0.7-and-49.0.0-before-49.0.4-http-response-splitting-via-wasi-http

    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-2026-121439 | CVE-DB