EUVD-2026-21037Published

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…

Exact source revision recorded 30 Oct 2026 05:52:24 UTC. It does not establish the source's current position. Latest evidence.

Recorded JSON

euvd · EUVD-2026-21037

Published

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.

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, 6:54:48 PM

dateUpdated: Apr 13, 2026, 8:18:21 PM

3 related source bulletins · separate from aliases

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

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

openSUSE-SU-2026:10715-1: libtree-sitter0_26-0.26.8-2.1 on GA media

CVE-2026-34941 · CVE-2026-34943 · CVE-2026-34988 · CVE-2026-35186

Source published: Apr 9, 2026, 6:54:48 PM (timezone not stated)
Source modified: Apr 13, 2026, 8:18:21 PM (timezone not stated)
Observed here: 30 Oct 2026 05:52:24 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:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N