CkbApplication · Nervos
CVE-2021-45700
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAn issue was discovered in the ckb crate before 0.40.0 for Rust. Attackers can cause a denial of service (Nervos CKB blockchain node crash) via a dead call that is used as a DepGroup.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThe ckb crate before version 0.40.0 for Rust contains a vulnerability where a dead call (a call that fails or returns no result) can be used as a DepGroup (dependency group), causing the Nervos CKB blockchain node to crash. Attackers can exploit this to cause denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
CkbApplication
< 0.40.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify the ckb crate version in useInspect your project's Cargo.lock file and search for the [[package]] name="ckb" entry. Note the version number listed (e.g., version = "0.39.0"). Alternatively, run `cargo tree -p ckb` to see the exact version being used.Affected if The ckb crate version is lower than 0.40.0 (e.g., 0.39.x, 0.38.x, etc.)
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Confirm the ckb crate is used as a runtime dependencyCheck your Cargo.toml file for ckb in the [dependencies] section. Verify it is not only a dev-dependency or build-dependency by reviewing the full dependency declaration.Affected if ckb is listed as a runtime dependency and the version is below 0.40.0
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Check if DepGroup functionality is being utilizedSearch your project source code for usage of DepGroup (search for "DepGroup" or "dep_group" in your .rs files). DepGroup is a Nervos CKB feature that groups dependencies for cell dependencies.Affected if Your code creates or uses DepGroup objects, and the ckb crate version is vulnerable
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Inspect cell dependency definitions for dead callsReview any code that constructs DepGroup objects. Look for cell dependencies where the referenced cell either fails during execution or returns no output (zero-length data). Check your type scripts or lock scripts that define cell dependencies.Affected if A DepGroup contains a reference to a cell that will fail or return no result at runtime, and the ckb crate version is below 0.40.0
You are affected if your project depends on the ckb crate at a version lower than 0.40.0 and your code or runtime configuration uses DepGroups that can contain dead (failing or empty) cell references.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped0.40.0
Upgrade the ckb crate to version 0.40.0 or later to resolve the vulnerability. This is a straightforward dependency version update in Cargo.toml.
ckb crate version 0.40.0
- Update the Cargo.toml file to specify ckb = "0.40.0" or use cargo update ckb to upgrade to the latest 0.40.x release
- Run cargo build or cargo update to fetch and compile the fixed version
- Rebuild and restart the Nervos CKB node service
- Verify the node starts successfully and is not crashing
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Ckb
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,144.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-45700 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-45700 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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