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…
Exact source revision recorded 30 Oct 2026 05:52:25 UTC. It does not establish the source's current position. Latest evidence.
euvd · EUVD-2026-21039
PublishedWasmtime 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.
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.
Original publisher date fields
datePublished: Apr 9, 2026, 6:55:56 PM
dateUpdated: Apr 13, 2026, 3:38:27 PM
2 related source bulletins · separate from aliases
openSUSE-SU-2026:20749-1: Security update for tree-sitter
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
SUSE-SU-2026:21789-1: Security update for tree-sitter
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
- Source published
- Apr 9, 2026, 6:55:56 PM (timezone not stated)
- Source modified
- Apr 13, 2026, 3:38:27 PM (timezone not stated)
- Observed here
- 30 Oct 2026 05:52:25 UTC
- Source terms
- ENISA EUVD · source terms and attribution apply
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.
EUVD CVSS 4.0 · 6.1 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