# What changed in browserslist

> 18 changes in browserslist 4 from its official release notes, upgrade guides and advisories: 1 breaking, 4 security, 1 new APIs and options. Each one cited. Sources checked 2026-10-17. HTML: https://unstale.sh/npm/browserslist/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## browserslist 4

### Breaking changes

- Removed the Baseline warning because it has its own warning. (4.28.1) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.1)

### Security

- Fixed config name loading protection on Windows. (4.29.1) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.29.1)
- Browserslist: Unbounded memory growth (no cache eviction) via distinct query results, leading to eventual OOM (4.28.7) — [security advisory](https://github.com/advisories/GHSA-C83G-RGW3-J3CX), [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.7)
- Browserslist: Uncaught crash / prototype write via untrusted browserslist-stats.json custom stats (normalizeStats) (4.28.7) — [security advisory](https://github.com/advisories/GHSA-73WF-GQ98-2V4G), [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.7)
- Fixes prototype pollution. (4.28.2) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.2)

### New APIs and options

- Added the BROWSERSLIST_TRACE_WARNING environment variable. (4.27.0) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.27.0)

### Performance

- Improves `or` parsing performance. (4.28.9) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.9)
- Parsing performance was improved. (4.28.7) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.7)

### Behavior and default changes

- Browserslist’s Firefox ESR data was updated, which may change the browser versions selected by matching queries. (4.29.3) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.29.3)
- Queries can now continue across lines and array entries, allowing multiline query configuration. (4.29.0) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.29.0)

### Fixes and other changes

- Fixed ignoring null usage in cover X in Y queries. (4.29.2) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.29.2)
- Fixed case-insensitive negation queries. (4.29.1) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.29.1)
- Fixed percentage and supports queries case-insensitive. (4.29.1) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.29.1)
- Fixed `including kaios` in baseline queries. (4.28.8) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.8)
- Fixed Electron version queries. (4.28.6) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.6)
- Fixed `>` and `>=` queries. (4.28.5) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.5)
- Fixed the SyntaxError regression introduced in 4.28.3. (4.28.4) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.4)
- Baseline queries are now case-insensitive. (4.28.3) — [release notes](https://github.com/browserslist/browserslist/releases/tag/4.28.3)