CVE-2026-45149
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 brace-expansion library generates arbitrary strings containing a common prefix and suffix. From 5.0.0 to before 5.0.6, the max option was being applied too late. When expanding a single large numeric range like {1..10000000}, the sequence generation loop generates all 10 million intermediate elements before the max limit is applied With max=10, the output is correctly limited to 10 items, but the process still allocates ~505 MB and spends ~800ms building the full intermediate array. This vulnerability is fixed in 5.0.6.
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 brace-expansion library applies the max limit option after generating the full sequence rather than during generation. When expanding large numeric ranges like {1..10000000}, all 10 million elements are created in memory before the max=10 limit is applied, resulting in ~505 MB allocation and ~800ms CPU usage despite the output being correctly limited to 10 items.
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>= 5.0.0, < 5.0.6CVSS 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 brace-expansion versionRun 'npm list brace-expansion' or check your package.json dependencies to find the installed versionAffected if version is 5.0.0 through 5.0.5 (anything < 5.0.6)
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Locate code using expand() with max optionSearch your codebase for calls to brace-expansion expand function that pass a max parameter, for example: expand('{1..N}', {max: M})Affected if your code passes a max option to expand() with large numeric ranges
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Review numeric range parametersAudit all brace expansion patterns in your code for numeric ranges like {1..1000} that could be exploited with very large upper boundsAffected if your application accepts or processes user-controlled numeric ranges in brace expansion patterns
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Monitor for large memory allocation patternsDuring runtime, observe memory usage when expand() is called with max and numeric ranges - memory spike indicates the full array is generated before truncationAffected if memory usage spikes significantly (hundreds of MB) when processing expand() with max option on numeric ranges
You are affected if brace-expansion version is < 5.0.6 AND your code uses the max option with numeric ranges that could expand to large sequences.
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 · scoped5.0.6
Upgrade brace-expansion to version 5.0.6 or later, which applies the max limit during sequence generation rather than after, preventing excessive memory allocation and CPU consumption.
[email protected] or higher
- Update the brace-expansion package to version 5.0.6 or higher using your package manager (e.g., npm install brace-expansion@^5.0.6, yarn add brace-expansion@^5.0.6, or pnpm add brace-expansion@^5.0.6)
- Verify the installed version is 5.0.6 or later by checking your lockfile or running npm list brace-expansion
- Test that large numeric range expansions (e.g., {1..10000000}) with max option now correctly limit memory allocation and execution time, not just the final output count
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-45149 — 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-2026-45149 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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