CVE-2026-115889 Wasmtime - Type Confusion

Wasmtime < 36.0.19 and < 43.0.0 contains a type confusion caused by bit-packing SSA value indices overflow in Cranelift compiler backend, letting attackers cause arbitrary miscompilation and escape Wasm sandbox, exploit requires crafted Wasm functions with many SSA values.

CVSS base score 9.9 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Required
EPSS
0.66% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Type Confusion
Impact
Remote Code Execution, Privilege Escalation
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Published
23 October 2026
Updated
25 October 2026
Weakness
CWE-197

Vendor fix

Update to versions 36.0.19 or 43.0.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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