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CRITICAL severity

CVE-2021-45698 — ckb

CRITICAL

CVE-2021-45698 is a critical-severity (CVSS 9.8) vulnerability in ckb. A fix is available for ckb — see the affected versions and patch details below.

RPC call failure in ckb

Also known asGHSA-v666-6w97-pcwmRUSTSEC-2021-0107
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs67th percentile — riskier than 67% of all scored CVEsHighest risk
0.00%0.56%1.13%1.69%0.4%1.2%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-45698 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🦀ckb

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🦀crates.iockball versions0.40.0cargo update -p ckb --precise 0.40.0

Affected Products

1 product · 1 configurations
Application
ckbnervos
< 0.40.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ckb, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update ckb to 0.40.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-45698 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

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.
O3 Security · Impact-Aware SCA

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CVE-2021-45698: ckb — Fixed in 0.40.0