CVE-2026-34945 | bytecodealliance wasmtime up to 36.0.6/42.0.1/44.0.0 return numeric conversion (GHSA-m9w2-8782-2946)

VDB-356656 · CVE-2026-34945 · GHSA-M9W2-8782-2946 BYTECODEALLIANCE WASMTIME UP TO 36.0.6/42.0.1/44.0.0 RETURN NUMERIC CONVERSION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 4.1 $0-$5k 0.84 Summaryinfo A vulnerability was found in bytecodealliance wasmtime up to 36.0.6/42.0.1/44.0.0. It has been declared as problematic. This vulnerability affects unknown code. Executing a manipulation of the argument return can lead to numeric conversion. This vulnerability is handled as CVE-2026-34945. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component. Detailsinfo A vulnerability has been found in bytecodealliance wasmtime up to 36.0.6/42.0.1/44.0.0 and classified as problematic. This vulnerability affects some unknown processing. The manipulation of the argument return with an unknown input leads to a numeric conversion vulnerability. The CWE definition for the vulnerability is CWE-681. When converting from one data type to another, such as long to integer, data can be omitted or translated in a way that produces unexpected values. If the resulting values are used in a sensitive context, then dangerous behaviors may occur. As an impact it is known to affect confidentiality. CVE summarizes: 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 contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosing data on the host's stack to WebAssembly guests. The host's stack can possibly contain sensitive data related to other host-originating operations which is not intended to be disclosed to guests. This bug specifically arose from a mistake where the return value of table.size was statically typed as a 32-bit integer, as opposed to consulting the table's index type to see how large the returned register could be. When combined with details about Wnich's ABI, such as multi-value returns, this can be combined to read stack data from the host, within a guest. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1. The advisory is shared for download at github.com. This vulnerability was named CVE-2026-34945 since 03/31/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. Upgrading to version 36.0.7, 42.0.2 or 44.0.1 eliminates this vulnerability. Productinfo Vendor bytecodealliance Name wasmtime Version 36.0.0 36.0.1 36.0.2 36.0.3 36.0.4 36.0.5 36.0.6 42.0.0 42.0.1 44.0 Website Product: https://github.com/bytecodealliance/wasmtime/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA CVSS-B Score: 🔒 CNA CVSS-BT Score: 🔒 CNA Vector: 🔒 CVSSv3info VulDB Meta Base Score: 4.3 VulDB Meta Temp Score: 4.1 VulDB Base Score: 4.3 VulDB Temp Score: 4.1 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Numeric conversion CWE: CWE-681 / CWE-704 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: wasmtime 36.0.7/42.0.2/44.0.1 Timelineinfo 03/31/2026 CVE reserved 04/09/2026 +9 days Advisory disclosed 04/09/2026 +0 days VulDB entry created 04/09/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: GHSA-m9w2-8782-2946 Status: Confirmed CVE: CVE-2026-34945 (🔒) GCVE (CVE): GCVE-0-2026-34945 GCVE (VulDB): GCVE-100-356656 Entryinfo Created: 04/09/2026 22:00 Changes: 04/09/2026 22:00 (67) Complete: 🔍 Cache ID: 99:BF0:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸