fix: upgrade brace-expansion transitive dep to patch CVE-2026-13149 (GHSA-3jxr-9vmj-r5cp)

[Copilot]

brace-expansion@5.0.6 has an O(2ⁿ) ReDoS via consecutive non-expanding {} groups — a ~90-byte input can block the Node.js event loop for minutes.

Changes

• package.json: Added a scoped npm override to force brace-expansion ≥ 5.0.7 within glob's dependency subtree (the only path pulling in the vulnerable version):

  "overrides": {
    "glob": {
      "brace-expansion": "^5.0.7"
    }
  }

• package-lock.json: Regenerated — node_modules/glob/node_modules/brace-expansion now resolves to 5.0.9 (was 5.0.6).

Reachability

Not reachable in production (high confidence). The vulnerable package enters via glob@13.0.6 → minimatch@10.2.5 → brace-expansion@5.0.6, where glob@13 is a dev-only dependency. No production source code calls brace-expansion.expand() directly or transitively. This update removes the vulnerability from the dev toolchain and satisfies vulnerability scanners.

Original prompt

---

This section details the Dependabot vulnerability alert you should resolve

<alert_title>brace-expansion: DoS via exponential-time expansion of consecutive non-expanding {} groups</alert_title>
<alert_description>### Summary
brace-expansion's expand() exhibits exponential-time - O(2ⁿ) - behavior in the number of consecutive non-expanding {} groups. A short, all-ASCII input (~90 bytes/30 groups) blocks the calling thread for minutes; a slightly longer input hangs it effectively indefinitely. Because the dominant consumers run on Node's single-threaded event loop, one small input can fully stall a worker/process.

In expand_, post is computed unconditionally at the top of the function, before the early-return branches that don't use it:

const post = m.post.length ? expand_(m.post, max, false) : [''];   // always recurses
  ...
if (!isSequence && !isOptions) {
  if (m.post.match(/,(?!,).*\}/)) {
    str = m.pre + '{' + m.body + escClose + m.post;
    return expand_(str, max, true); // restart — `post` discarded
  }
  return [str];
}

For input like a{},{},…, the first {} is non-expanding, so control reaches the {a},b} rewrite branch - but expand_ has already recursed into post over the entire remaining tail, only to throw the result away.
Each level therefore spawns two recursive expansions over essentially the same remaining work: T(n) = 2·T(n−1) ⇒ O(2ⁿ).

The max option does not mitigate this: max only bounds the output-building loops; neither the post recursion nor the rewrite recursion consults it.

Measured on 5.0.6:

groups (n)	input bytes	time
20	60	130 ms
24	72	1.9 s
26	78	7.8 s
30 (PoC)	90	~2 min

Proof of concept

const { expand } = require('brace-expansion');
// 30 non-expanding groups, ~90 bytes — blocks for minutes:
expand('a{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{}');

Impact

Any application that passes attacker-influenced strings to brace-expansion.expand() - directly or transitively via minimatch/glob brace patterns - can be driven into a multi-minute-to-indefinite CPU hang by a tiny request, denying service on that thread/process.

Remediation

Upgrade to a patched release. The fix:

1. Defers computing post until after the early-return branches (and computes it locally in the $-suffix branch), so post is only expanded when a brace set actually expands and the value is used. This alone removes the exponential.
2. Converts the {a},b} rewrite from recursion to an in-function loop, so a long run of rewrites cannot grow the call stack.

Verified: the PoC drops from ~2 min to 0.55 ms, 5,000 groups complete in ~344 ms, and output is identical to 5.0.6 across a behavioral-equivalence suite (sequences, padding, $-prefix, a{},b}c, {},a}b, x{{a,b}}y, etc.). Post-fix complexity is ~O(n²) on this input class - acceptable for the security fix; a linear rewrite can be a non-urgent follow-up.

If immediate upgrade isn't possible, avoid passing untrusted input to expand() / glob brace patterns, or run such expansion under a timeout/worker.</alert_description>

high
GHSA-3jxr-9vmj-r5cp, CVE-2026-13149
brace-expansion
npm
<vulnerable_versions>5.0.6</vulnerable_versions>
<patched_version>5.0.7</patched_version>
<manifest_path>package-lock.json</manifest_path>

https://github.com/juliangruber/brace-expansion/security/advisories/GHSA-3jxr-9vmj-r5cp https://nvd.nist.gov/vuln/detail/CVE-2026-13149 https://github.com/juliangruber/brace-expansion/pull/122 https://github.com/juliangruber/brace-expansion/pull/123 https://github.com/juliangruber/brace-expansion/commit/835d6be91201122d9adffb0c0c8c094189ace265 https://github.com/juliangruber/brace-expansion/commit/c7e33ec13ac1a684c116720843ce24e208611754 https://github.com/juliangruber/brace-expansion/commit/d74e63030c012e3b7ae81657b8d665619cd51b95 https://github.com/juliangruber/brace-expansion/releases/tag/v1.1.16 https://github.com/juliangruber/brace-expansion/releases/tag/v2.1.2 https://github.com/juliangruber/brace-expansion/releases/tag/v5.0.7 https://www.npmjs.com/package/brace-expansion https://github.com/advisories/GHSA-3jxr-9vmj-r5cp

<agent_instructions>@copilot please go through the issues mentioned here, identify all issues, and assess whether they can be fixed.
Recommend the necessary changes.
If it is not a breaking change, let's log the issue.
Please verify all test cases and validate the runs.
</agent_instructions>

<task_instructions>Resolve this alert by updating the affected package to a non-vulnerable version. Prefer the lowest non-vulnerable version (see the patched_version field above) over the latest to minimize breaking changes. Include a Reachability ...

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