minimatch is a minimal matching utility for converting glob expressions into JavaScript RegExp objects. Prior to 11.0.1, src/index.ts implements firstPhasePreProcess() so that, at optimizationLevel 2 or higher, it repeatedly expands attacker-controlled **/.. pattern segments inside a fixpoint loop, allowing generated globParts entries to be processed and expanded again. secondPhasePreProcess() then compares the expanded entries pairwise, so a short malicious glob can cause excessive CPU and memory consumption during pattern compilation. This issue is fixed in version 11.0.1.

Affected: npm: minimatch

minimatch 10.2.6 contains an attacker-controlled pattern amplification in firstPhasePreProcess() when optimizationLevel >= 2.

researcher: Reid Downing (b1nv0id) files:

- src/index.ts: 690-770 - src/index.ts: 780-796

issue: input-controlled growth of globParts during first-phase preprocessing, followed by quadratic second-phase processing.

the **/../ transformation clones a globparts entry and appends the clone to the same globparts array: ``` parts.splice(gs, 1) const other = parts.slice(0) other[gs] = '**' globParts.push(other) ``` this occurs inside a do...while (didSomething) fixpoint loop, allowing generated entries to be processed again.

the expanded globparts array is subsequently processed by secondPhasePreProcess(), which performs pairwise comparisons: ``` for (let i = 0; i < globParts.length - 1; i++) { for (let j = i + 1; j < globParts.length; j++) { this.partsMatch(...) } } ``` an attacker who can supply a glob pattern can therefore cause additional pattern entries to be generated during preprocessing, followed by quadratic pairwise processing, resulting in excessive cpu and memory consumption.

Affected: Ubuntu:Pro:14.04:LTS: node-minimatch, Ubuntu:Pro:16.04:LTS: node-minimatch, Ubuntu:18.04:LTS: node-minimatch, Ubuntu:20.04:LTS: node-minimatch, Ubuntu:22.04:LTS: node-minimatch, Ubuntu:24.04:LTS: node-minimatch, Ubuntu:26.10: node-minimatch, Ubuntu:26.04:LTS: node-minimatch

minimatch is a minimal matching utility for converting glob expressions into JavaScript RegExp objects. Prior to 11.0.1, src/index.ts implements firstPhasePreProcess() so that, at optimizationLevel 2 or higher, it repeatedly expands attacker-controlled **/.. pattern segments inside a fixpoint loop, allowing generated globParts entries to be processed and expanded again. secondPhasePreProcess() then compares the expanded entries pairwise, so a short malicious glob can cause excessive CPU and memory consumption during pattern compilation. This issue is fixed in version 11.0.1.