{"id":"EUVD-2026-21039","revision":null,"records":[{"revision":"ba0fde3a3a11421d8218e90df7c86922","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-35195","aliases":[],"title":"Wasmtime has an out-of-bounds write or crash when transcoding component model strings","description":"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.","state":0,"publishedAt":"2026-04-09T18:55:56.467+00:00","modifiedAt":"2026-04-13T15:38:27.294+00:00","affected":[{"ecosystem":"Vendor product","name":"wasmtime","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"bytecodealliance\",\n                    \"product\": \"wasmtime\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 24.0.7\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 25.0.0, < 36.0.7\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 37.0.0, < 42.0.2\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \">= 43.0.0, < 44.0.1\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"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","score":6.1,"severity":"MEDIUM"}],"references":["https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-394w-hwhg-8vgm"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-35195","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-35195","identifiers":["CVE-2026-35195"]},"retained":false,"historicalAffected":[]},{"revision":"28ba34fd76bd41988dad6c4462562064","observedAt":"2026-11-01T06:08:18.226+00:00","statement":{"source":"euvd","id":"EUVD-2026-21039","aliases":["CVE-2026-35195","GHSA-394w-hwhg-8vgm"],"title":"Wasmtime is a runtime for WebAssembly. 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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.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","vector":"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","score":6.1,"severity":null}],"references":["https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-394w-hwhg-8vgm"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-21039","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Apr 9, 2026, 6:55:56 PM","dateUpdated":"Apr 13, 2026, 3:38:27 PM"},"relatedAdvisories":[{"id":"openSUSE-SU-2026:20749-1","title":"Security update for tree-sitter","vulnerabilityIds":["CVE-2026-34941","CVE-2026-34942","CVE-2026-34943","CVE-2026-34944","CVE-2026-34945","CVE-2026-34946","CVE-2026-34987","CVE-2026-34988","CVE-2026-35186","CVE-2026-35195"]},{"id":"SUSE-SU-2026:21789-1","title":"Security update for tree-sitter","vulnerabilityIds":["CVE-2026-34941","CVE-2026-34942","CVE-2026-34943","CVE-2026-34944","CVE-2026-34945","CVE-2026-34946","CVE-2026-34987","CVE-2026-34988","CVE-2026-35186","CVE-2026-35195"]}],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-21039","identifiers":["EUVD-2026-21039","CVE-2026-35195","GHSA-394w-hwhg-8vgm"]},"retained":false,"historicalAffected":[]},{"revision":"a9ec3dfe328941f09fc7350cfaed95ca","observedAt":"2026-10-27T09:03:08.102+00:00","statement":{"source":"nvd","id":"CVE-2026-35195","aliases":[],"title":"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 be…","description":"Wasmtime is a runtime for WebAssembly. 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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. 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Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-35195","identifiers":["CVE-2026-35195"]},"retained":false,"historicalAffected":[]},{"revision":"f1b8ab489e6846ea83b735b3a9e776ae","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"GHSA-394w-hwhg-8vgm","aliases":["CVE-2026-35195","RUSTSEC-2026-0091"],"title":"Wasmtime has out-of-bounds write or crash when transcoding component model strings","description":"### Impact\n\nWasmtime'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.\n\nWasmtime 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. \n\n### Patches\n\nWasmtime 24.0.7, 36.0.7, 42.0.2, and 43.0.1 have been issued to fix this bug. Users are recommended to update to these patched versions of Wasmtime.\n\n### Workarounds\n\nThere is no known workaround for this issue and affected hosts/embeddings are recommended to upgrade.","state":0,"publishedAt":"2026-04-09T20:24:12+00:00","modifiedAt":"2026-09-10T03:50:42.3755974+00:00","affected":[{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"24.0.7"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"25.0.0"},{"kind":"fixed","version":"36.0.7"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"37.0.0"},{"kind":"fixed","version":"42.0.2"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"43.0.0"},{"kind":"fixed","version":"43.0.1"}]}],"versions":["43.0.0"],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"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","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-394w-hwhg-8vgm","https://nvd.nist.gov/vuln/detail/CVE-2026-35195","https://github.com/bytecodealliance/wasmtime","https://rustsec.org/advisories/RUSTSEC-2026-0091.html"],"sourceUrl":"https://github.com/advisories/GHSA-394w-hwhg-8vgm","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-394w-hwhg-8vgm","identifiers":["GHSA-394w-hwhg-8vgm","CVE-2026-35195","RUSTSEC-2026-0091"]},"retained":false,"historicalAffected":[]},{"revision":"a2b89ca25f1142f59aa69a0e321b43bf","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"RUSTSEC-2026-0091","aliases":["CVE-2026-35195","GHSA-394w-hwhg-8vgm"],"title":"Out-of-bounds write or crash when transcoding component model strings","description":"This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-394w-hwhg-8vgm\nFor more information see the GitHub-hosted security advisory.","state":0,"publishedAt":"2026-04-09T12:00:00+00:00","modifiedAt":"2026-10-12T18:00:08.828955+00:00","affected":[{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0.0.0-0"},{"kind":"fixed","version":"24.0.7"},{"kind":"introduced","version":"25.0.0"},{"kind":"fixed","version":"36.0.7"},{"kind":"introduced","version":"37.0.0"},{"kind":"fixed","version":"42.0.2"},{"kind":"introduced","version":"43.0.0"},{"kind":"fixed","version":"43.0.1"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"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","score":null,"severity":null}],"references":["https://crates.io/crates/wasmtime","https://rustsec.org/advisories/RUSTSEC-2026-0091.html","https://github.com/bytecodealliance/wasmtime/pull/13026"],"sourceUrl":"https://osv.dev/vulnerability/RUSTSEC-2026-0091","license":"OSV · upstream source license applies","key":"osv:RUSTSEC-2026-0091","identifiers":["RUSTSEC-2026-0091","CVE-2026-35195","GHSA-394w-hwhg-8vgm"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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