CVE-2026-35195 (GCVE-0-2026-35195)
Vulnerability from cvelistv5 – Published: 2026-04-09 18:55 – Updated: 2026-04-09 18:55
VLAI?
Title
Wasmtime has an out-of-bounds write or crash when transcoding component model strings
Summary
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings between components contains a bug where the return value of a guest component's realloc is not validated before the host attempts to write through the pointer. This enables a guest to cause the host to write arbitrary transcoded string bytes to an arbitrary location up to 4GiB away from the base of linear memory. These writes on the host could hit unmapped memory or could corrupt host data structures depending on Wasmtime's configuration. Wasmtime by default reserves 4GiB of virtual memory for a guest's linear memory meaning that this bug will by default on hosts cause the host to hit unmapped memory and abort the process due to an unhandled fault. Wasmtime can be configured, however, to reserve less memory for a guest and to remove all guard pages, so some configurations of Wasmtime may lead to corruption of data outside of a guest's linear memory, such as host data structures or other guests's linear memories. This vulnerability is fixed in 24.0.7, 36.0.7, 42.0.2, and 43.0.1.
Severity ?
CWE
- CWE-787 - Out-of-bounds Write
Assigner
References
| URL | Tags | ||||
|---|---|---|---|---|---|
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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": {
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"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"
}
]
}
],
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}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"baseScore": 6.1,
"baseSeverity": "MEDIUM",
"privilegesRequired": "LOW",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N",
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"providerMetadata": {
"dateUpdated": "2026-04-09T18:55:56.467Z",
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"shortName": "GitHub_M"
},
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"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-394w-hwhg-8vgm"
}
],
"source": {
"advisory": "GHSA-394w-hwhg-8vgm",
"discovery": "UNKNOWN"
},
"title": "Wasmtime has an out-of-bounds write or crash when transcoding component model strings"
}
},
"cveMetadata": {
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"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-35195",
"datePublished": "2026-04-09T18:55:56.467Z",
"dateReserved": "2026-04-01T18:48:58.936Z",
"dateUpdated": "2026-04-09T18:55:56.467Z",
"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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