What is CVE-2026-34942?

CVE-2026-34942 is a medium-severity vulnerability in Bytecodealliance Wasmtime, classified under Improper Validation of Array Index. CVSS score: 6.5/10. Published 2026-04-09.

How severe is CVE-2026-34942?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Vulnerability in Bytecodealliance Wasmtime

CVE-2026-34942

Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings into the Component Model's utf16 or latin1+utf16 encodings improperly verified the alignment of reallocate…

EPSS: 0.004 (27.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Affected products

Bytecodealliance Wasmtime — versions < 24.0.7, >= 25.0.0, < 36.0.7, >= 37.0.0, < 42.0.2

Weakness classification (CWE)

CWE-129 — Improper Validation of Array Index

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2026-34942?: CVE-2026-34942 is a medium-severity vulnerability in Bytecodealliance Wasmtime, classified under Improper Validation of Array Index. CVSS score: 6.5/10. Published 2026-04-09.
How severe is CVE-2026-34942?: Medium severity. CVSS v3 base score is 6.5 out of 10.