CVE-2020-37056
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 · uneditedCrystal Shard http-protection 0.2.0 contains an IP spoofing vulnerability that allows attackers to bypass protection middleware by manipulating request headers. Attackers can hardcode consistent IP values across X-Forwarded-For, X-Client-IP, and X-Real-IP headers to circumvent security checks and gain unauthorized access.
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 http-protection Crystal Shard library <=0.2.0 trusts client-supplied IP headers (X-Forwarded-For, X-Client-IP, X-Real-IP) without proper validation, allowing attackers to spoof their source IP address and bypass IP-based access controls and rate limiting.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 http-protection as a project dependencyExamine your project's shard.yml file for http-protection under dependencies, or check shard.lock for the installed versionAffected if http-protection is listed as a dependency with version <=0.2.0 or no version pin that resolves to <=0.2.0
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Verify the installed http-protection versionRun 'shards version' or inspect the version field in shard.lock for the http-protection entryAffected if The installed version is 0.2.0 or lower
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Locate http-protection configuration in your applicationSearch source files for 'HttpProtection' or 'http_protection' module initialization, typically in config or main application fileAffected if The library is instantiated and configured in your application code
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Determine if client-supplied headers are being trustedSearch for code that passes X-Forwarded-For, X-Client-IP, or X-Real-IP headers to trust or ip_headers configuration options, or inspect the HttpProtection::Configuration objectAffected if The configuration explicitly trusts or uses X-Forwarded-For, X-Client-IP, or X-Real-IP headers without additional validation
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Check if IP-based access controls or rate limiting rely on http-protectionSearch for usage of HttpProtection::IPAccess or rate limiting middleware that references the trusted headersAffected if Access control lists or rate limiters depend on the potentially spoofed IP from client-supplied headers
You are affected if http-protection version 0.2.0 or lower is in use and your application configuration trusts X-Forwarded-For, X-Client-IP, or X-Real-IP headers for access control or rate limiting decisions.
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 dataReplace trust in client-supplied headers with validated source IP from the underlying TCP connection, or upgrade to a patched version of http-protection that implements proper IP validation and origin verification.
- Consultation4.0 h
- Implementation8.0 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 $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-37056 — 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-2020-37056 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
- No weaponised exploit code, or anything meant to cause harm
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