TextApplication · Golang
CVE-2020-14040
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 x/text package before 0.3.3 for Go has a vulnerability in encoding/unicode that could lead to the UTF-16 decoder entering an infinite loop, causing the program to crash or run out of memory. An attacker could provide a single byte to a UTF16 decoder instantiated with UseBOM or ExpectBOM to trigger an infinite loop if the String function on the Decoder is called, or the Decoder is passed to golang.org/x/text/transform.String.
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 golang.org/x/text package before version 0.3.3 has a vulnerability in its UTF-16 decoder where a single byte input to a decoder instantiated with UseBOM or ExpectBOM can cause an infinite loop when the String function is called, leading to denial of service via crash or memory exhaustion.
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
TextApplication
< 0.3.3
FedoraOperating system
= 32CVSS 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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Check golang.org/x/text versionRun 'go list -m all' in your project directory, or inspect your go.mod file for 'golang.org/x/text' entry, or check vendor directory if presentAffected if The version listed is less than 0.3.3 (e.g., 0.3.2, 0.3.1, 0.3.0, etc.)
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Identify UTF-16 decoder usage in codeSearch source code files for imports of 'golang.org/x/text/encoding/unicode/utf16' and usage of utf16.NewDecoder APIAffected if Code imports and uses the UTF-16 decoder package from golang.org/x/text
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Verify decoder instantiation with BOM optionsSearch for decoder instantiation with UseBOM or ExpectBOM options in source code (e.g., utf16.NewDecoder(utf16.UseBOM) or similar patterns)Affected if The UTF-16 decoder is created with UseBOM or ExpectBOM configuration option
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Confirm String method is called on the decoderSearch for .String() method calls on UTF-16 decoder instances in your codebaseAffected if The vulnerable decoder configuration from step 3 has its String method invoked with input data
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Check for single-byte input handlingReview code paths where single-byte data may be passed to the UTF-16 decoder's String methodAffected if Your application passes potentially single-byte inputs to the BOM-configured UTF-16 decoder's String function
You are affected only if golang.org/x/text version is below 0.3.3 AND your code uses the UTF-16 decoder with UseBOM or ExpectBOM option AND calls the String function with single-byte input data.
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 data0.3.3
Update golang.org/x/text to version 0.3.3 or later to obtain the patched UTF-16 decoder implementation.
Fix this in Text
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-14040 — 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-2020-14040 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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