Medium 4.1Published Jan 27, 2026

CVE-2026-24116Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64

Updated under an hour ago (Oct 27, 2026, 1:40 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for bytecodealliance wasmtime

Exploited in the last 30 days

Wasmtime is a runtime for WebAssembly. Starting in version 29.0.0 and prior to version 36.0.5, 40.0.3, and 41.0.1, on x86-64 platforms with AVX, Wasmtime's compilation of the `f64.copysign` WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabled this can result in a uncaught segfault due to loading from unmapped guard pages. With guard pages disabled it's possible for out-of-sandbox data to be loaded, but unless there is another bug in Cranelift this data is not visible to WebAssembly guests. Wasmtime 36.0.5, 40.0.3, and 41.0.1 have been released to fix this issue. Users are recommended to upgrade to the patched versions of Wasmtime. Other affected versions are not patched and users should updated to supported major version instead. This bug can be worked around by enabling signals-based-traps. While disabling guard pages can be a quick fix in some situations, it's not recommended to disabled guard pages as it is a key defense-in-depth measure of Wasmtime.

CVSS: 4.1 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-125
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jan 27, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

bytecodealliance wasmtime bytecodealliance:wasmtime (from the name)	from 29.0.0, < 36.0.5; from 37.0.0, < 40.0.3; = 41.0.0	CNA record
bytecodealliance wasmtime bytecodealliance:wasmtime	from 29.0.0 before 36.0.5; from 40.0.0 before 40.0.3; from 41.0.0 before 41.0.1	NVD

References

References

https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-vc8c-j3xm-xj73	x-refsource-confirm, patch, vendor-advisory
https://github.com/bytecodealliance/wasmtime/commit/728fa07184f8da2a046f48ef9b61f869dce133a6	x-refsource-misc, patch
https://github.com/bytecodealliance/wasmtime/commit/799585fc362fcb991de147dd1a9f2ba0861ed440	x-refsource-misc, patch
https://github.com/bytecodealliance/wasmtime/commit/ac92d9bb729ad3a6d93f0724c4c33a0c4a9c0227	x-refsource-misc, patch
https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.memory_guard_size	x-refsource-misc, product
https://docs.rs/wasmtime/latest/wasmtime/struct.Config.html#method.signals_based_traps	x-refsource-misc, product
https://docs.wasmtime.dev/stability-release.html	x-refsource-misc, release-notes
https://rustsec.org/advisories/RUSTSEC-2026-0006.html	x-refsource-misc, third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.