Ws RsApplication · Ws Rs Project
CVE-2020-35896
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 ws crate through 2020-09-25 for Rust. The outgoing buffer is not properly limited, leading to a remote memory-consumption attack.
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 ws crate for Rust has an unbounded outgoing buffer that allows remote attackers to consume excessive server memory. By sending numerous small WebSocket frames that accumulate without proper size limits, an attacker can exhaust server resources leading to 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
Ws RsApplication
<= 0.9.1CVSS 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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Locate the ws crate dependencySearch your project for the ws crate by inspecting Cargo.toml and Cargo.lock files for 'ws' under [dependencies] or [package] sectionsAffected if The ws crate appears as a direct or transitive dependency with version 0.9.1 or lower
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Identify the installed versionIn Cargo.lock, find the [[package]] entry with name 'ws' and check the 'version' field (e.g., version = "0.9.0")Affected if The version is 0.9.1 or any version lower than 0.9.1
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Confirm server usageSearch your source code for Server::new, listen, or ws::WebSocket::new patterns that indicate inbound WebSocket server functionalityAffected if The project implements a WebSocket server using the ws crate (not just a client)
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Check for buffer configurationInspect source code for any configure, settings, or buffer-related method calls on the WebSocket object (e.g., builder configurations)Affected if No explicit outgoing buffer size limits are configured (the vulnerability exists when default unbounded buffer behavior is used)
You are affected if your project depends on ws-rs version 0.9.1 or lower and operates a WebSocket server without custom buffer limits configured.
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.
From vendor dataUpdate the ws crate to a version that implements proper outgoing buffer limits. Consider adding rate limiting or connection throttling as additional defense-in-depth measures while the fix is being deployed.
Fix this in Ws Rs
Scoped from the published advisory
- Consultation2.0 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 $2,464.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-35896 — 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-2020-35896 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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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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