CVE-2026-34944 (GCVE-0-2026-34944)
Vulnerability from cvelistv5 – Published: 2026-04-09 18:38 – Updated: 2026-04-09 18:38
VLAI?
Title
Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on x86-64
Summary
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, On x86-64 platforms with SSE3 disabled Wasmtime's compilation of the f64x2.splat WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it's possible for out-of-sandbox data to be loaded, but this data is not visible to WebAssembly guests. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.
Severity ?
CWE
- CWE-248 - Uncaught Exception
Assigner
References
| URL | Tags | ||||
|---|---|---|---|---|---|
|
|||||
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| bytecodealliance | wasmtime |
Affected:
< 24.0.7
Affected: >= 25.0.0, < 36.0.7 Affected: >= 37.0.0, < 42.0.2 Affected: >= 43.0.0, < 44.0.1 |
{
"containers": {
"cna": {
"affected": [
{
"product": "wasmtime",
"vendor": "bytecodealliance",
"versions": [
{
"status": "affected",
"version": "\u003c 24.0.7"
},
{
"status": "affected",
"version": "\u003e= 25.0.0, \u003c 36.0.7"
},
{
"status": "affected",
"version": "\u003e= 37.0.0, \u003c 42.0.2"
},
{
"status": "affected",
"version": "\u003e= 43.0.0, \u003c 44.0.1"
}
]
}
],
"descriptions": [
{
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"value": "Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, On x86-64 platforms with SSE3 disabled Wasmtime\u0027s compilation of the f64x2.splat WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it\u0027s possible for out-of-sandbox data to be loaded, but this data is not visible to WebAssembly guests. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"baseScore": 4.1,
"baseSeverity": "MEDIUM",
"privilegesRequired": "LOW",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "ACTIVE",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-248",
"description": "CWE-248: Uncaught Exception",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-04-09T18:38:16.182Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
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"name": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-qqfj-4vcm-26hv",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-qqfj-4vcm-26hv"
}
],
"source": {
"advisory": "GHSA-qqfj-4vcm-26hv",
"discovery": "UNKNOWN"
},
"title": "Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on x86-64"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-34944",
"datePublished": "2026-04-09T18:38:16.182Z",
"dateReserved": "2026-03-31T17:27:08.660Z",
"dateUpdated": "2026-04-09T18:38:16.182Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
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}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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