What is CVE-2023-6245?

CVE-2023-6245 is a high-severity uncontrolled resource consumption vulnerability in candid (rust), affecting versions >= 0.9.0, < 0.9.10. It is fixed in 0.9.10. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.

How severe is CVE-2023-6245?

CVE-2023-6245 has a CVSS score of 7.5 (High). 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 candid are affected by CVE-2023-6245?

candid (rust) versions >= 0.9.0, < 0.9.10 is affected.

Is there a fix for CVE-2023-6245?

Yes. CVE-2023-6245 is fixed in 0.9.10. Upgrade to this version or later.

Is CVE-2023-6245 exploitable, and should I be worried?

Whether CVE-2023-6245 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.

What actually determines whether CVE-2023-6245 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-2023-6245?

Upgrade candid to 0.9.10 or later.

CVE-2023-6245 in candid

Q: How severe is CVE-2023-6245?

CVE-2023-6245 has a CVSS score of 7.5 (High). 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.

Q: Which versions of candid are affected by CVE-2023-6245?

candid (rust) versions >= 0.9.0, < 0.9.10 is affected.

Q: Is there a fix for CVE-2023-6245?

Yes. CVE-2023-6245 is fixed in 0.9.10. Upgrade to this version or later.

Q: Is CVE-2023-6245 exploitable, and should I be worried?

Whether CVE-2023-6245 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.

Q: What actually determines whether CVE-2023-6245 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.

Q: How do I fix CVE-2023-6245?

Upgrade candid to 0.9.10 or later.

Summary

Candid infinite decoding loop through specially crafted payload

Unaffected

Rust canisters using candid < 0.9.0 or >= 0.9.10
Rust canister interfaces of type other than record { * }
Motoko based canisters
dfx (for asset canister) <= 0.14.3 or >= 0.15.2

Workarounds

There is no workaround for canisters using the affected versions of candid other than upgrading to patched version.

References

Impact

The Candid library causes a Denial of Service while parsing a specially crafted payload with empty data type. For example, if the payload is record { * ; empty } and the canister interface expects record { * } then the rust candid decoder treats empty as an extra field required by the type. The problem with type empty is that the candid rust library wrongly categorizes empty as a recoverable error when skipping the field and thus causing an infinite decoding loop.

Canisters using affected versions of candid are exposed to denial of service by causing the decoding to run indefinitely until the canister traps due to reaching maximum instruction limit per execution round. Repeated exposure to the payload will result in degraded performance of the canister.

For asset canister users, dfx versions >= 0.14.4 to <= 0.15.2-beta.0 ships asset canister with an affected version of candid.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2023-6245 has a CVSS score of 7.5 (High). The vector is network-reachable, no 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 (0.9.10); upgrading removes the vulnerable code path.

Affected versions

candid (>= 0.9.0, < 0.9.10)

Security releases

candid → 0.9.10 (rust)

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.

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Remediation advice

The issue has been patched in 0.9.10. All rust based canisters on candid versions >= 0.9.0 must upgrade their candid versions to >= 0.9.10 and deploy their canisters to mainnet as soon as possible.

Frequently Asked Questions

What is CVE-2023-6245? CVE-2023-6245 is a high-severity uncontrolled resource consumption vulnerability in candid (rust), affecting versions >= 0.9.0, < 0.9.10. It is fixed in 0.9.10. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
How severe is CVE-2023-6245? CVE-2023-6245 has a CVSS score of 7.5 (High). 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 candid are affected by CVE-2023-6245? candid (rust) versions >= 0.9.0, < 0.9.10 is affected.
Is there a fix for CVE-2023-6245? Yes. CVE-2023-6245 is fixed in 0.9.10. Upgrade to this version or later.
Is CVE-2023-6245 exploitable, and should I be worried? Whether CVE-2023-6245 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-2023-6245 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-2023-6245? Upgrade candid to 0.9.10 or later.