{"id":"CVE-2026-35186","revision":null,"records":[{"revision":"8c1cc421c1b3417e9c78242c949d4628","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-35186","aliases":[],"title":"Wasmtime has an improperly masked return value from `table.grow` with Winch compiler backend","description":"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 backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","state":0,"publishedAt":"2026-04-09T18:54:48.76+00:00","modifiedAt":"2026-04-13T20:18:21.954+00:00","affected":[{"ecosystem":"Vendor product","name":"wasmtime","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"bytecodealliance\",\n                    \"product\": \"wasmtime\",\n                    \"versions\": [\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:H/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-f984-pcp8-v2p7"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-35186","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-35186","identifiers":["CVE-2026-35186"]},"retained":false,"historicalAffected":[]},{"revision":"0bffcc1b24fe4b5498f552f824e4bf26","observedAt":"2026-11-01T06:08:17.085+00:00","statement":{"source":"euvd","id":"EUVD-2026-21037","aliases":["CVE-2026-35186","GHSA-f984-pcp8-v2p7"],"title":"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 backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables…","description":"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 backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 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:H/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-f984-pcp8-v2p7"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-21037","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Apr 9, 2026, 6:54:48 PM","dateUpdated":"Apr 13, 2026, 8:18:21 PM"},"relatedAdvisories":[{"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"]},{"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":"openSUSE-SU-2026:10715-1","title":"libtree-sitter0_26-0.26.8-2.1 on GA media","vulnerabilityIds":["CVE-2026-34941","CVE-2026-34943","CVE-2026-34988","CVE-2026-35186"]}],"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-2026-21037","identifiers":["EUVD-2026-21037","CVE-2026-35186","GHSA-f984-pcp8-v2p7"]},"retained":false,"historicalAffected":[]},{"revision":"996d4f9884f44a4b9df2ed30d8799e96","observedAt":"2026-10-27T09:03:08.102+00:00","statement":{"source":"nvd","id":"CVE-2026-35186","aliases":[],"title":"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 backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables…","description":"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 backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed. The primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of table.grow that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes. Overall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.","state":0,"publishedAt":"2026-04-09T19:16:25.343+00:00","modifiedAt":"2026-10-26T22:10:00.163+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","score":6.1,"severity":"MEDIUM"},{"system":"CVSS 3.1 · 134c704f-9b21-4f2e-91b3-4a467353bcc0 · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-f984-pcp8-v2p7"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-35186","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-789"],"productCriteria":["cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*","cpe:2.3:a:bytecodealliance:wasmtime:43.0.0:*:*:*:*:rust:*:*"],"sourceDates":{"published":"2026-04-09T19:16:25.343","lastModified":"2026-10-26T22:10:00.163"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-35186","identifiers":["CVE-2026-35186"]},"retained":false,"historicalAffected":[]},{"revision":"98232ab8da82454191ce6539cd6b0f43","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"GHSA-f984-pcp8-v2p7","aliases":["CVE-2026-35186","RUSTSEC-2026-0094"],"title":"Wasmtime has improperly masked return value from `table.grow` with Winch compiler backend","description":"### Impact\n\nWasmtime's Winch compiler backend contains a bug where translating the `table.grow` operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the operator, internally in Winch, is tagged as a 64-bit value instead of a 32-bit value. This invalid internal representation of Winch's compiler state compounds into further issues depending on how the value is consumed.\n\nOne example can be seen when the result of `table.grow` is used as the address of a load operation. The load operation is tricked into thinking the address is a 64-bit value, not a 32-bit value, which means that the final address to load from is calculated incorrectly. This can lead to a situation where the bytes before the start of linear memory can be loaded/stored to.\n\nThe primary consequence of this bug is that bytes in the host's address space can be stored/read from. This is only applicable to the 16 bytes before linear memory, however, as the only significant return value of `table.grow` that can be misinterpreted is -1. The bytes before linear memory are, by default, unmapped memory. Wasmtime will detect this fault and abort the process, however, because wasm should not be able to access these bytes.\n\nOverall this this bug in Winch represents a DoS vector by crashing the host process, a correctness issue within Winch, and a possible leak of up to 16-bytes before linear memory. Wasmtime's default compiler is Cranelift, not Winch, and Wasmtime's default settings are to place guard pages before linear memory. This means that Wasmtime's default configuration is not affected by this issue, and when explicitly choosing Winch Wasmtime's otherwise default configuration leads to a DoS. Disabling guard pages before linear memory is required to possibly leak up to 16-bytes of host data.\n\n### Patches\n\nWasmtime 43.0.1, 42.0.2, and 36.0.7 have been released with fixes for this issue.\n\n### Workaround\n\nThere are no workarounds within the Winch compiler backend while using the affected versions. Users of Wasmtime are encouraged either to upgrade to patched versions or, if that is not possible, use the Cranelift compiler backend.","state":0,"publishedAt":"2026-04-10T15:32:49+00:00","modifiedAt":"2026-09-10T03:51:01.5917594+00:00","affected":[{"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:H/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-f984-pcp8-v2p7","https://nvd.nist.gov/vuln/detail/CVE-2026-35186","https://github.com/bytecodealliance/wasmtime","https://rustsec.org/advisories/RUSTSEC-2026-0094.html"],"sourceUrl":"https://github.com/advisories/GHSA-f984-pcp8-v2p7","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-f984-pcp8-v2p7","identifiers":["GHSA-f984-pcp8-v2p7","CVE-2026-35186","RUSTSEC-2026-0094"]},"retained":false,"historicalAffected":[]},{"revision":"ae41b6ebe243474db779f61507d004d6","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"RUSTSEC-2026-0094","aliases":["CVE-2026-35186","GHSA-f984-pcp8-v2p7"],"title":"Improperly masked return value from `table.grow` with Winch compiler backend","description":"This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-f984-pcp8-v2p7\nFor more information see the GitHub-hosted security advisory.","state":0,"publishedAt":"2026-04-09T12:00:00+00:00","modifiedAt":"2026-10-12T18:00:08.3314929+00:00","affected":[{"ecosystem":"crates.io","name":"wasmtime","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0.0.0-0"},{"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:H/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-2026-0094.html","https://github.com/bytecodealliance/wasmtime/pull/13014"],"sourceUrl":"https://osv.dev/vulnerability/RUSTSEC-2026-0094","license":"OSV · upstream source license applies","key":"osv:RUSTSEC-2026-0094","identifiers":["RUSTSEC-2026-0094","CVE-2026-35186","GHSA-f984-pcp8-v2p7"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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