{"cve":"CVE-2026-34983","nvd":{"published":"2026-04-09T19:16:24.850","modified":"2026-10-26T21:10:00.170","status":"Analyzed","description":"Wasmtime is a runtime for WebAssembly. In 43.0.0, cloning a wasmtime::Linker is unsound and can result in use-after-free bugs. This bug is not controllable by guest Wasm programs. It can only be triggered by a specific sequence of embedder API calls made by the host. Specifically, the following steps must occur to trigger the bug clone a wasmtime::Linker, drop the original linker instance, use the new, cloned linker instance, resulting in a use-after-free. This vulnerability is fixed in 43.0.1.","cvss_v4":{"vector":"CVSS:4.0/AV:P/AC:H/AT:P/PR:H/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N","score":1.0},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H","score":5.0},"cwes":["CWE-416"],"references":["https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2","https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-hfr4-7c6c-48w2"],"products":["bytecodealliance:wasmtime"],"source":"nvd","synced_at":"2026-10-26T21:38:48.864438205+00:00"},"epss":{"cve":"CVE-2026-34983","score":0.00117,"percentile":0.01646,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-hfr4-7c6c-48w2","url":"https://osv.dev/vulnerability/GHSA-hfr4-7c6c-48w2","summary":"Wasmtime has use-after-free bug after cloning `wasmtime::Linker`","modified":"2026-09-10T03:51:01.950251061Z","packages":[{"ecosystem":"crates.io","name":"wasmtime","purl":"pkg:cargo/wasmtime","ranges":[">=43.0.0 <43.0.1"],"fixed":["43.0.1"]}]},{"id":"PYSEC-2026-151","url":"https://osv.dev/vulnerability/PYSEC-2026-151","summary":"","modified":"2026-05-21T15:00:24.330171463Z","packages":[{"ecosystem":"PyPI","name":"wasmtime","purl":"pkg:pypi/wasmtime","ranges":["<=43.0.0"],"fixed":[]}]},{"id":"RUSTSEC-2026-0090","url":"https://osv.dev/vulnerability/RUSTSEC-2026-0090","summary":"Use-after-free bug after cloning `wasmtime::Linker`","modified":"2026-10-12T18:00:09.243186370Z","packages":[{"ecosystem":"crates.io","name":"wasmtime","purl":"pkg:cargo/wasmtime","ranges":[">=43.0.0 <43.0.1"],"fixed":["43.0.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}