BoringApplication · Cloudflare
CVE-2023-6180
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 · uneditedThe tokio-boring library in version 4.0.0 is affected by a memory leak issue that can lead to excessive resource consumption and potential DoS by resource exhaustion. The set_ex_data function used by the library did not deallocate memory used by pre-existing data in memory each time after completing a TLS connection causing the program to consume more resources with each new connection.
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 · high confidenceThe tokio-boring library (a Rust async wrapper around BoringSSL for TLS) version 4.0.0 has a memory leak in its set_ex_data function. After each TLS connection completes, the function fails to deallocate memory used by pre-existing external data, causing memory to accumulate with every new connection and potentially leading to resource exhaustion and DoS.
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
BoringApplication
= 4.0.0CVSS 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
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 if tokio-boring or Cloudflare Boring is presentSearch your project dependencies (Cargo.toml, Cargo.lock) for 'tokio-boring' or 'cloudflare-boring' entries. Also check any vendored dependencies or lockfiles.Affected if Either tokio-boring or Cloudflare Boring is listed as a dependency
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Determine the installed versionExamine the version number in Cargo.lock or query the installed crate version using 'cargo tree' or your package manager. For Cloudflare Boring specifically, check if version 4.0.0 is installed.Affected if The installed version is exactly 4.0.0 for either tokio-boring or Cloudflare Boring
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Verify TLS connections are being madeReview your application code to confirm it uses the tokio-boring library to establish TLS connections. Check for usage of connect(), accept(), or similar TLS handshake functions from tokio-boring.Affected if Your application uses tokio-boring to handle TLS connections (incoming or outgoing)
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Monitor for memory accumulationObserve the process memory usage over time using system monitoring tools (such as top, htop, or process-specific memory profilers). Compare memory usage before and after multiple TLS connection cycles.Affected if Memory usage grows continuously with each new TLS connection and does not stabilize or decrease
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Check for connection pooling configurationInspect your application configuration or code to determine if connection pooling is implemented. Look for connection pool size limits, reuse logic, or pool management code.Affected if Connection pooling with explicit limits is NOT configured, allowing unlimited new connections to accumulate unfreed memory
You are affected if your environment has tokio-boring or Cloudflare Boring version 4.0.0 installed and your application uses it to handle TLS connections, with memory accumulating over time.
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 dataUsers should upgrade to a patched version of tokio-boring once available. As a workaround, implement connection pooling with limits and monitor memory usage to detect exploitation.
Fix this in Boring
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,616.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-6180 — 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-2023-6180 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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