Affected: juliangruber brace-expansion

brace-expansion through 5.0.6 is vulnerable to denial of service. The expand() function exhibits exponential-time complexity in the number of consecutive non-expanding '{}' brace groups. An attacker who passes a crafted string to expand(), directly or transitively, can cause significant CPU consumption and event-loop blocking. The max option does not mitigate this, as it bounds the output size rather than the recursion work.

Affected: npm: js-yaml

# Quadratic CPU consumption in `!!omap` resolution (js-yaml 3.x and 4.x)

## Summary

`resolveYamlOmap()` enforces key uniqueness for `!!omap` sequences with a linear scan (`objectKeys.indexOf(...)`) inside the per-element loop, making resolution **O(n²)** in the number of entries. A modestly sized YAML document therefore consumes disproportionate CPU inside `yaml.load()`, giving a denial of service against any consumer that parses untrusted YAML.

`!!omap` is registered in the **default schema** (`lib/schema/default.js` → `require('../type/omap')`), so a plain `yaml.load(untrustedInput)` with no options is affected — no custom schema or non-default configuration is required.

**This is the same weakness as CVE-2026-59870 / GHSA-724g-mxrg-4qvm**, which was fixed in the 5.x line in 5.2.1. That fix was never backported: both currently maintained legacy lines still carry the original implementation.

## Affected versions

| Line | Latest tested | Status | |---|---|---| | 3.x | **3.15.0** | Affected — `objectKeys.indexOf(pairKey)` at `lib/type/omap.js:29` | | 4.x | **4.3.0** | Affected — `objectKeys.indexOf(pairKey)` at `lib/type/omap.js:30` | | 5.x | 5.2.2 | **Not affected** — fixed in 5.2.1 (uses a `Set`) |

Both figures are the newest release of each line at the time of writing, so this is not a "you are on an old version" issue.

## Details

`lib/type/omap.js` (js-yaml 4.3.0):

```js if (objectKeys.indexOf(pairKey) === -1) objectKeys.push(pairKey) else return false ```

`obj…