RUSTSEC-2021-0107: Miner fails to get block template when a cell used as a cell dep has been destroyed.

What to do

1. See which version you have: cargo tree -i ckb (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p ckb. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example ckb = "0.40.0") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

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.

Patch

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.

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.

References

• Package: crates.io/crates/ckb
• Advisory: rustsec.org/advisories/RUSTSEC-2021-0107.html
• Web: github.com/nervosnetwork/ckb/commit/e5b45795375d7dc2a689fb46790caca5c2653638

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.

Other advisories for ckb

• VulnerabilityRUSTSEC-2021-0108 · 2021-07-25Remote memory exhaustion in ckb
• VulnerabilityRUSTSEC-2021-0109 · 2021-07-25Process crashes when the cell used as DepGroup is not alive
• VulnerabilityGHSA-29c2-65rj-h343 · 2024-02-03Nervos CKB Permit load cell data from memory
• VulnerabilityGHSA-29c2-65rj-h343 · 2024-02-03Nervos CKB Permit load cell data from memory
• VulnerabilityGHSA-29c2-65rj-h343 · 2024-02-03Nervos CKB Permit load cell data from memory
• VulnerabilityGHSA-29c2-65rj-h343 · 2024-02-03Nervos CKB Permit load cell data from memory
• VulnerabilityGHSA-29c2-65rj-h343 · 2024-02-03Nervos CKB Permit load cell data from memory
• VulnerabilityGHSA-3gjh-29fv-8hr6 · 2024-02-03Nervos CKB Snappy decompress length can be very large and causes out of memory error

Full security history of ckb