CVE-2026-24116

Host process crash via widened f64.copysign load

Published Jan 27, 2026 · Updated Jan 27, 2026

Out-of-bounds read in Wasmtime allows guest OS users to crash the host process via a crafted WebAssembly module. Cranelift's x86-64 AVX lowering of f64.copysign sinks an 8-byte f64.load into a 16-byte vector load, reading up to eight bytes past the valid boundary. The crash requires guard pages, disabled signals-based traps, and execution of attacker-controlled guest code; default settings convert the fault into a safe guest trap.

CVSS severity4.1
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Wasmtime allows guest OS users to crash the host process via a crafted WebAssembly module. Cranelift's x86-64 AVX lowering of f64.copysign sinks an 8-byte f64.load into a 16-byte vector load, reading up to eight bytes past the valid boundary. The crash requires guard pages, disabled signals-based traps, and execution of attacker-controlled guest code; default settings convert the fault into a safe guest trap.

The record

CVE
CVE-2026-24116
Published
Jan 27, 2026
Updated
Jan 27, 2026
Vendor
Bytecode Alliance
Product
Wasmtime
Classifications
CWE-125, T1499.004
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Jan 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 29.0.0, < 36.0.5
  2. Affected versionversion=>= 37.0.0, < 40.0.3
  3. Affected versionversion== 41.0.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Bytecode Alliance · Wasmtimeversion=>= 29.0.0, < 36.0.5; version=>= 37.0.0, < 40.0.3; version== 41.0.0

Published CVSS scores

4.1GitHub, Inc.CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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