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Fencer Vulns
high 8.4

CVE-2025-66627 json

Wasmi's Linear Memory has a Critical Use After Free Vulnerability

published 2025-12-08 11 mo ago modified 2026-10-14 25 d ago also EUVD-2025-201826 , GHSA-g4v2-cjqp-rfmq

cvss
8.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

Wasmi is a WebAssembly interpreter focused on constrained and embedded systems. In versions 0.41.0, 0.41.1, 0.42.0 through 0.47.1, 0.50.0 through 0.51.2 and 1.0.0, Wasmi's linear memory implementation leads to a Use After Free vulnerability, triggered by a WebAssembly module under certain memory growth conditions. This issue potentially leads to memory corruption, information disclosure, or code execution. This issue is fixed in versions 0.41.2, 0.47.1, 0.51.3 and 1.0.1. To workaround this issue, consider limiting the maximum linear memory sizes where feasible.

Patch / fix

  • crates.io wasmi 0.41.2, 0.47.1, 0.51.3, 1.0.1
  • wasmi-labs wasmi 0.41.2, 0.47.1, 0.51.3, 1.0.1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
11 mo ago

Exploit prediction

0.15% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.4 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 8.4 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
crates.io wasmi
>=0.41.0, <0.41.2
>=0.42.0, <0.47.1
>=0.50.0, <0.51.3
>=1.0.0, <1.0.1
0.41.2
0.47.1
0.51.3
1.0.1

Affected products

  • wasmi-labs wasmi

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.