Quick answers
- Is CVE-2026-115388 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-115388 being exploited in the wild.
- How severe is CVE-2026-115388?
- Medium severity, with a CVSS score of 6.2, published 22 October 2026.
- Which products and versions are affected?
- Bytecode Alliance Wasmtime before 36.0.16, 37.0.0 through 48.0.2, 49.0.0.
- Is there a fix for CVE-2026-115388?
- Yes: fixed in 36.0.16, 48.0.3, 49.0.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-115388 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-115388?
- Check whether you run Bytecode Alliance Wasmtime at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: 36.0.16, 48.0.3, 49.0.1
Technical details
The wasmtime-wasi-http component does not enforce the wasi:io/streams check-write allowance for WASIp2 outgoing HTTP body writes. A guest can call check-write to learn the permitted write size (typically 1MB), then pass a much larger buffer to write which succeeds instead of trapping as required by the spec. Each outgoing-body resource can hold a host memory allocation for the store's lifetime, enabling guest-driven memory exhaustion with no privilege requirements and local attack vector.
Affected products
- Bytecode Alliance Wasmtime before 36.0.16, 37.0.0 through 48.0.2, 49.0.0
Timeline
- 2026-09-24: disclosed
- 2026-10-22: advisory