Memory Management Flaw in Wasmtime Runtime for WebAssembly
CVE-2026-24116

4.1MEDIUM

Key Information:

Vendor

Bytecodealliance

Status
Wasmtime
Vendor
CVE Published:
27 January 2026

What is CVE-2026-24116?

Wasmtime, a runtime for WebAssembly, has a vulnerability that affects versions prior to 36.0.5, 40.0.3, and 41.0.1. On x86-64 platforms utilizing AVX instructions, the compilation of the f64.copysign WebAssembly instruction may inaccurately load excess bytes, potentially leading to unhandled segmentation faults in scenarios where signals-based traps are disabled. This flaw allows for the possibility of unintended data being accessed from unmapped guard pages, although it's generally not visible to WebAssembly guests unless another bug exists within Cranelift. To mitigate this vulnerability, users are encouraged to upgrade to the specified patched versions. Maintaining guard pages is critical for the security of Wasmtime and disabling them is not recommended.

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Deploy the Patch

Affected Version(s)

wasmtime >= 29.0.0, < 36.0.5 < 29.0.0, 36.0.5

wasmtime >= 37.0.0, < 40.0.3 < 37.0.0, 40.0.3

wasmtime = 41.0.0 = 41.0.0

References

https://github.com/bytecodealliance/wasmtime/security/adv...
x_refsource_CONFIRM
https://github.com/bytecodealliance/wasmtime/commit/728fa...
x_refsource_MISC
https://github.com/bytecodealliance/wasmtime/commit/79958...
x_refsource_MISC

CVSS V4

Score:
4.1
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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