What is CVE-2026-115391?

CVE-2026-115391 is a medium-severity vulnerability in Bytecodealliance Wasmtime, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.8/10. Published 2026-10-22.

How severe is CVE-2026-115391?

Medium severity. CVSS v3 base score is 5.8 out of 10.

Resource exhaustion in Bytecodealliance Wasmtime

CVE-2026-115391

Wasmtime 46.0.0 before 46.0.3 and 47.0.0 before 47.0.4 contains an uncontrolled resource allocation vulnerability in its WASIp3 implementation that buffers guest-specified-length writes on the host without limit. Malicious guests can offer large buffers to WASIp3 file or HTTP write streams, causing the host to copy and buffer all bytes, bounded only by guest linear memory, exhausting host memory.

Published 2026-10-22 · last modified 2026-10-22.

CVSS v3 metric

CVSS v3 base score 5.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Bytecodealliance Wasmtime

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

github.com/bytecodealliance/wasmtime/security/advisories/GHSA-x84v-gj2h-g759 (vendor-advisory)
www.vulncheck.com/advisories/wasmtime-46.0.0-before-46.0.3-and-47.0.0-before-47… (third-party-advisory)

Frequently asked questions

What is CVE-2026-115391?: CVE-2026-115391 is a medium-severity vulnerability in Bytecodealliance Wasmtime, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.8/10. Published 2026-10-22.
How severe is CVE-2026-115391?: Medium severity. CVSS v3 base score is 5.8 out of 10.