CVE-2026-115391 Wasmtime 46.0.0 before 46.0.3 and 47.0.0 before 47.0.4 Unbounded Heap Allocation via WASIp3 Streams
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-115391?
CVE-2026-115391 is a medium-severity vulnerability in bytecodealliance wasmtime, published on 22 Oct 2026.
Official description
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.
Weakness: CWE-770
Which versions are affected by CVE-2026-115391?
1 open source package ship an affected version, including wasmtime.
| Package | Affected | Fixed in |
|---|---|---|
wasmtime crates.io | From 46.0.0 | 46.0.3, 47.0.4 |
How do I fix CVE-2026-115391?
Upgrade wasmtime to a fixed version for your release line: 46.0.3 or 47.0.4.
Is CVE-2026-115391 being exploited?
There is no known exploitation of CVE-2026-115391 in the wild and no public exploit code.
Sources
Also known as GHSA-6862-f859-6m9r, GHSA-x84v-gj2h-g759, RUSTSEC-2026-0268, UBUNTU-CVE-2026-115391.