Vulnerability · Published Feb 24, 2026 · Assigned by GitHub_M
CVE-2026-27204Wasmtime WASI implementations are vulnerable to guest-controlled resource exhaustion
Medium 6.9
In plain English
A medium-severity uncontrolled resource consumption in wasmtime from bytecodealliance. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Wasmtime is a runtime for WebAssembly. Prior to versions 24.0.6, 36.0.6, 4.0.04, 41.0.4, and 42.0.0, Wasmtime's implementation of WASI host interfaces are susceptible to guest-controlled resource exhaustion on the host. Wasmtime did not appropriately place limits on resource allocations requested by the guests. This serves as a Denial of Service vector. Wasmtime 24.0.6, 36.0.6, 40.0.4, 41.0.4, and 42.0.0 have all been released with the fix for this issue. These versions do not prevent this issue in their default configuration to avoid breaking preexisting behaviors. All versions of Wasmtime have appropriate knobs to prevent this behavior, and Wasmtime 42.0.0-and-later will have these knobs tuned by default to prevent this issue from happening. There are no known workarounds for this issue without upgrading. Embedders are recommended to upgrade and configure their embeddings as necessary to prevent possibly-malicious guests from triggering this issue.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:13 | rust-wasmtime | no fix listed | DEBIAN-CVE-2026-27204 |
| Debian:14 | rust-wasmtime | 36.0.6+dfsg-1 | DEBIAN-CVE-2026-27204 |
| Ubuntu:24.04:LTS | rust-wasmtime | no fix listed | UBUNTU-CVE-2026-27204 |
| Ubuntu:25.10 | rust-wasmtime | no fix listed | UBUNTU-CVE-2026-27204 |
| Ubuntu:26.04:LTS | rust-wasmtime | no fix listed | UBUNTU-CVE-2026-27204 |
| Ubuntu:26.10 | rust-wasmtime | no fix listed | UBUNTU-CVE-2026-27204 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| bytecodealliance | wasmtime | < 24.0.6>= 25.0.0, < 36.0.6>= 37.0.0, < 40.0.4>= 41.0.0, < 41.0.4 |
Weakness: CWE-400, CWE-770, CWE-774, CWE-789 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H
References
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-852m-cvvp-9p4w x_refsource_CONFIRM
- https://github.com/bytecodealliance/wasmtime/issues/11552 x_refsource_MISC
- https://github.com/bytecodealliance/wasmtime/pull/12599 x_refsource_MISC
- https://docs.rs/wasmtime-wasi/latest/wasmtime_wasi/struct.WasiCtxBuilder.html#method.max_random_size x_refsource_MISC
- https://docs.rs/wasmtime/latest/wasmtime/component/struct.ResourceTable.html#method.set_max_capacity x_refsource_MISC
- https://docs.rs/wasmtime/latest/wasmtime/struct.Store.html#method.set_hostcall_fuel x_refsource_MISC
- https://docs.wasmtime.dev/security-what-is-considered-a-security-vulnerability.html x_refsource_MISC