Summary
Workarounds
If upgrading is not possible it's recommended to use config.reference_types(false). That will disable these modules at validation-time which prevents the possibility of a panic at runtime. If reference-types are required, however, then there is no other workaround at this time other than upgrading.
References
Impact
The 19.0.0 release of Wasmtime contains a regression introduced during its development which can lead to a guest WebAssembly module causing a panic in the host runtime. A valid WebAssembly module, when executed at runtime, may cause this panic. The panic in question is caused when a WebAssembly module issues a table.* instruction which uses a dropped element segment with a table that also has an externref type. This causes Wasmtime to erroneously use an empty function segment instead of an empty externref segment to perform this operation. This mismatch in types causes a panic in Wasmtime when it's asserted that an externref table is only viewed as externrefs.
This regression was introduced during the development of the 19.0.0 release and only affects the 19.0.0 release. This panic requires the reference-types WebAssembly feature to be enabled, and it is enabled by default. Toolchains are not known to generate this pattern by default so it's likely a module would need to be specifically crafted to trigger this panic.
A panic in a host runtime represents a possible denial-of-service in some scenarios. This panic cannot introduce memory unsafety or allow WebAssembly to break outside of its sandbox, however. There is no possible heap corruption or memory unsafety from this panic.
An object is accessed using a type that is incompatible with its actual type, causing the runtime to interpret memory incorrectly. Typical impact: memory safety violations, unexpected behavior, or code execution.
CVE-2024-30266 has a CVSS score of 3.3 (Low). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (19.0.1); upgrading removes the vulnerable code path.
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 19.0.1 has been released to fix this problem. Users of 19.0.0 should upgrade to 19.0.1. All other versions of Wasmtime are not affected by this issue.
Frequently Asked Questions
- What is CVE-2024-30266? CVE-2024-30266 is a low-severity type confusion vulnerability in wasmtime (rust), affecting versions = 19.0.0. It is fixed in 19.0.1. An object is accessed using a type that is incompatible with its actual type, causing the runtime to interpret memory incorrectly.
- How severe is CVE-2024-30266? CVE-2024-30266 has a CVSS score of 3.3 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of wasmtime are affected by CVE-2024-30266? wasmtime (rust) versions = 19.0.0 is affected.
- Is there a fix for CVE-2024-30266? Yes. CVE-2024-30266 is fixed in 19.0.1. Upgrade to this version or later.
- Is CVE-2024-30266 exploitable, and should I be worried? Whether CVE-2024-30266 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-2024-30266 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-2024-30266? Upgrade
wasmtimeto 19.0.1 or later.