CVE-2026-34945

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Source
https://cve.org/CVERecord?id=CVE-2026-34945
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-34945.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-34945
Aliases
Downstream
Related
Published
2026-04-09T18:40:48.446Z
Modified
2026-04-22T05:14:14.082955411Z
Severity
  • 2.3 (Low) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N CVSS Calculator
Summary
Wasmtime leaks host data with 64-bit tables and Winch
Details

Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosing data on the host's stack to WebAssembly guests. The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests. This bug specifically arose from a mistake where the return value of table.size was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34945.json",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "introduced": "43.0.0"
                },
                {
                    "fixed": "44.0.1"
                }
            ],
            "source": "AFFECTED_FIELD"
        }
    ],
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-681"
    ]
}
References

Affected packages

Git / github.com/bytecodealliance/wasmtime

Affected ranges

Type
GIT
Repo
https://github.com/bytecodealliance/wasmtime
Events
Introduced
0b195ef5db76c02fb5392ec1418c58bdc5537d41
Fixed
09539085b9b514b65d5c51e2905dc38f6eb414b9
Introduced
7b3d6ae79e9153a2477668062f5622c10333925f
Fixed
403f9929d4e13ed87c76471d4f4bc8d381c876eb
Database specific 
{
    "extracted_events": [
        {
            "introduced": "25.0.0"
        },
        {
            "fixed": "36.0.7"
        },
        {
            "introduced": "37.0.0"
        },
        {
            "fixed": "42.0.2"
        }
    ],
    "source": "AFFECTED_FIELD"
}

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-34945.json"