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Vulnerability · Published Oct 23, 2026 · Assigned by GitHub_M

CVE-2026-115893Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction

Critical 9.9

In plain English

A critical-severity security flaw in wasmtime from bytecodealliance. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 63% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)9.9Critical
Exploit odds (30 days)1.0%top 37.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

Official description

Wasmtime is a runtime for WebAssembly. Prior to 36.0.19, 48.0.7, and 49.0.4, the Cranelift compiler backend on aarch64 can compile a Wasm br_table instruction with more than approximately 256,000 targets so that it has an incorrect conditional branch target. The branch can then jump to arbitrary other code at a user-controlled offset, allowing a user-controlled Wasm module to escape the sandbox on aarch64 engines using the default Cranelift backend. This issue is fixed in versions 36.0.19, 48.0.7, and 49.0.4.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:13rust-wasmtimeno fix listedDEBIAN-CVE-2026-115893
Debian:14rust-wasmtime36.0.20+dfsg-1DEBIAN-CVE-2026-115893
Ubuntu:24.04:LTSrust-wasmtimeno fix listedUBUNTU-CVE-2026-115893
Ubuntu:26.04:LTSrust-wasmtimeno fix listedUBUNTU-CVE-2026-115893
Ubuntu:26.10rust-wasmtimeno fix listedUBUNTU-CVE-2026-115893

Affected products (as reported)

VendorProductVersions
bytecodealliance wasmtime < 36.0.19>= 37.0.0, < 48.0.7>= 49.0.0, < 49.0.4

Weakness: CWE-691 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References