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chore(deps): update dependency brace-expansion@>=2.0.0 <2.1.2 to v5 [security] - #2139

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chore(deps): update dependency brace-expansion@>=2.0.0 <2.1.2 to v5 [security]#2139
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renovate/npm-brace-expansion-=2.0.0-2.1.2-vulnerability

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This PR contains the following updates:

Package Change Age Confidence
brace-expansion@>=2.0.0 <2.1.2 [^2.1.2^5.0.8](https://renovatebot.com/diffs/npm/brace-expansion@>=2.0.0 <2.1.2/2.1.2/5.0.8) age confidence

brace-expansion: DoS via unbounded expansion length causing an out-of-memory process crash

CVE-2026-14257 / GHSA-mh99-v99m-4gvg

More information

Details

Summary

expand() bounds the number of results it produces (the max option,
100_000 by default) but not their length. By chaining many brace groups,
an attacker keeps the result count under max while making every result grow
with the number of groups. Building max long results — plus the intermediate
arrays combined at each brace group — exhausts memory and crashes the Node
process with an uncatchable out-of-memory error. try/catch around
expand() does not help: the fatal error terminates the process.

A ~7.5 KB input ('{a,b}'.repeat(1500)) is enough to crash a default Node
process.

Details

For N chained brace groups such as '{a,b}'.repeat(N):

  • the result count is 2^N, immediately capped at max (100_000), so the
    max protection appears to hold, but
  • each result is N characters long, so the total output size is
    max × N characters, which grows without bound in N.

expand_ combines each brace set with the fully-expanded tail:

const post = m.post.length ? expand_(m.post, max, false) : ['']
...
for (let j = 0; j < N.length; j++) {
  for (let k = 0; k < post.length && expansions.length < max; k++) {
    const expansion = pre + N[j] + post[k]   // grows one group longer per level
    ...
    expansions.push(expansion)
  }
}

The loop guard expansions.length < max limits how many strings are built, but
nothing limits how long they get. Each recursion level materializes another
array of up to max strings, one character longer than the level below, and —
because V8 represents pre + N[j] + post[k] as a cons-string (rope) that
references post[k] — those intermediate strings stay reachable through the
whole chain. Memory therefore scales with max × N.

Measured on 5.0.7 ('{a,b}'.repeat(N), default max):

groups (N) input bytes result count peak RSS
20 100 100,000 ~80 MB
50 250 100,000 ~214 MB
100 500 100,000 ~409 MB
300 1,500 100,000 ~1,148 MB
1500 7,500 OOM crash
Proof of concept
const { expand } = require('brace-expansion')

// ~7.5 KB input — crashes the process with a fatal, uncatchable OOM:
//   FATAL ERROR: ... JavaScript heap out of memory
try {
  expand('{a,b}'.repeat(1500))
} catch (e) {
  // never reached — the process is already dead
}
Impact

Any application that passes attacker-influenced strings to
brace-expansion.expand() — directly, or transitively via minimatch / glob
brace patterns — can be crashed by a small request. Because the failure is a
fatal V8 out-of-memory error rather than a thrown exception, it cannot be caught
and it takes down the whole worker/process, denying service.

Remediation

Upgrade to a patched release. The fix bounds the total number of characters a
single expand() call may accumulate (EXPANSION_MAX_LENGTH, default
4_000_000, configurable via a new maxLength option), applied inside the
output-building loops so intermediate arrays are bounded too. Once the limit is
reached, output is truncated — consistent with how max already truncates —
instead of growing without bound. The limit sits well above any realistic
expansion (100,000 results hitting max measure ~1M characters), so legitimate
input is unaffected.

After the fix, '{a,b}'.repeat(1500) returns a bounded, truncated result in
~0.7 s using ~340 MB and never crashes, including under a constrained 512 MB
heap.

The fix bounds memory but the algorithm still rebuilds intermediate arrays at
each level (roughly O(N × maxLength) work on this input class). A streaming
rewrite that produces output in O(total output size) can be a non-urgent
follow-up.

If immediate upgrade isn't possible, avoid passing untrusted input to
expand() / glob brace patterns, or pass a small explicit max and
maxLength.

Severity

  • CVSS Score: 7.5 / 10 (High)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).


Release Notes

juliangruber/brace-expansion (brace-expansion@>=2.0.0 <2.1.2)

v5.0.8

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v5.0.7

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v5.0.6

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v5.0.5

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v5.0.4

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v5.0.3

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v5.0.2

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v4.0.1

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v4.0.0

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As a precaution to not risk breaking anything with 278132b, this is a new semver major release

v3.0.3

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v3.0.2

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v3.0.1

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v3.0.0

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@renovate
renovate Bot requested a review from a team as a code owner July 27, 2026 19:24
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changeset-bot Bot commented Jul 27, 2026

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⚠️ No Changeset found

Latest commit: a47d288

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

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@renovate
renovate Bot force-pushed the renovate/npm-brace-expansion-=2.0.0-2.1.2-vulnerability branch 2 times, most recently from 5b2ae31 to b1f0c85 Compare July 27, 2026 20:32
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@renovate
renovate Bot force-pushed the renovate/npm-brace-expansion-=2.0.0-2.1.2-vulnerability branch from b1f0c85 to a47d288 Compare July 27, 2026 20:36
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