An issue was discovered in the ckb crate before 0.40.0 for Rust. A get_block_template RPC call may fail in situations where it is supposed to select a Nervos CKB blockchain transaction with a higher fee rate than another transaction.

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

An issue was discovered in the ckb crate before 0.40.0 for Rust. A get_block_template RPC call may fail in situations where it is supposed to select a Nervos CKB blockchain transaction with a higher fee rate than another transaction.

Source published

26 Dec 2021 21:49:38 UTC

Source modified

4 Aug 2024 04:47:02 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

An issue was discovered in the ckb crate before 0.40.0 for Rust. A get_block_template RPC call may fail in situations where it is supposed to select a Nervos CKB blockchain transaction with a higher fee rate than another transaction.

Source published

Dec 26, 2021, 9:49:38 PM (timezone not stated)

Source modified

Aug 4, 2024, 4:47:02 AM (timezone not stated)

Observed here

9 Nov 2026 23:08:40 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

An issue was discovered in the ckb crate before 0.40.0 for Rust. A get_block_template RPC call may fail in situations where it is supposed to select a Nervos CKB blockchain transaction with a higher fee rate than another transaction.

Source published

27 Dec 2021 00:15:09 UTC

Source modified

17 Jun 2026 04:13:58 UTC

Observed here

24 Oct 2026 19:17:37 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Primary · 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS 2.0 · [email protected] · Primary · 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

An issue was discovered in the ckb crate before 0.40.0 for Rust. A get_block_template RPC call may fail in situations where it is supposed to select a Nervos CKB blockchain transaction with a higher fee rate than another transaction.

Source published

6 Jan 2022 22:10:43 UTC

Source modified

8 Nov 2023 04:07:22 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Publisher rating · CRITICAL

### 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 1. Submit transaction B when A is already on chain. 2. 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. 3. Ensure the fee rate of B is less than A so A always has higher priority.

Source published

25 Aug 2021 21:01:21 UTC

Source modified

8 Nov 2023 04:07:22 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

Publisher rating · HIGH

## 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.

Source published

25 Jul 2021 12:00:00 UTC

Source modified

12 Oct 2026 18:00:03 UTC

Observed here

24 Oct 2026 13:19:54 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.