Summary
Workarounds
There are no known workarounds at this time, embedders are encouraged to update to a patched version of Wasmtime.
Resources
Impact
Wasmtime's implementation of the wasi:http/types.fields resource is susceptible to panics when too many fields are added to the set of headers. Wasmtime's implementation in the wasmtime-wasi-http crate is backed by a data structure which panics when it reaches excessive capacity and this condition was not handled gracefully in Wasmtime. Panicking in a WASI implementation is a Denial of Service vector for embedders and is treated as a security vulnerability in Wasmtime.
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Wasmtime 24.0.6, 36.0.6, 40.0.4, 41.0.4, and 42.0.0 patch this vulnerability and return a trap to the guest instead of panicking.
Frequently Asked Questions
- What is CVE-2026-27572? CVE-2026-27572 is a medium-severity allocation of resources without limits or throttling vulnerability in wasmtime (rust), affecting versions < 24.0.6. It is fixed in 24.0.6, 36.0.6, 40.0.4. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- Which versions of wasmtime are affected by CVE-2026-27572? wasmtime (rust) versions < 24.0.6 is affected.
- Is there a fix for CVE-2026-27572? Yes. CVE-2026-27572 is fixed in 24.0.6, 36.0.6, 40.0.4. Upgrade to this version or later.
- Is CVE-2026-27572 exploitable, and should I be worried? Whether CVE-2026-27572 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-27572 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-27572?
- Upgrade
wasmtimeto 24.0.6 or later - Upgrade
wasmtimeto 36.0.6 or later - Upgrade
wasmtimeto 40.0.4 or later
- Upgrade