Summary
Miner fails to get block template when a cell used as a cell dep has been destroyed.
Workaround
- Submit transaction B when A is already on chain.
- Let B depend on A explicitly, there are several solutions:
- a. Add any output cell on A as a dep cell or input in B.
- b. Merge A and B. CKB allows using the same cell as both dep and input in the same transaction.
- Ensure the fee rate of B is less than A so A always has higher priority.
Impact
The RPC get_block_template fails when a cell has been used as a cell dep and an input in the different transactions.
Say cell C is used as a dep group in the transaction A, and is destroyed in the transaction B.
The node adds transaction A first, then B into the transaction pool. They are both valid. But when generating the block template, if the fee rate of B is higher, it comes before A, which will invalidate A. Currently the RPC get_block_template will fail instead of dropping A.
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.
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See it in your environmentNew to Kodem? Get a demo →Remediation advice
First, the get_block_template should not fail but dropping the conflict transactions.
Then we can propose solution to this issue. Here is an example. When a transaction is added to the pool, the pool must consider it depending on all the transactions which dep cell (direct or indirect via dep group) has been destroyed in this transaction. Because future transactions using the destroyed cells as dep will be rejected, the spending transaction only need to wait for all the existing dep transactions on chain.
Frequently Asked Questions
- What is GHSA-V666-6W97-PCWM? GHSA-V666-6W97-PCWM is a high-severity security vulnerability in ckb (rust), affecting versions < 0.40.0. It is fixed in 0.40.0.
- Which versions of ckb are affected by GHSA-V666-6W97-PCWM? ckb (rust) versions < 0.40.0 is affected.
- Is there a fix for GHSA-V666-6W97-PCWM? Yes. GHSA-V666-6W97-PCWM is fixed in 0.40.0. Upgrade to this version or later.
- Is GHSA-V666-6W97-PCWM exploitable, and should I be worried? Whether GHSA-V666-6W97-PCWM 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 GHSA-V666-6W97-PCWM 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 GHSA-V666-6W97-PCWM? Upgrade
ckbto 0.40.0 or later.