The brace-expansion library generates arbitrary strings containing a common prefix and suffix. Prior to 1.1.18, 2.1.4, 3.0.6, and 5.0.9, expand() does not apply maxLength while constructing comma-alternative intermediate arrays or padded sequences, allowing attacker-controlled input to exhaust memory or block the event loop. The fix for CVE-2026-14257 is bypassed by the vulnerability. This issue is fixed in versions 1.1.18, 2.1.4, 3.0.6, and 5.0.9.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
Potential Mitigations
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/147.html
- https://cwe.mitre.org/data/definitions/227.html
- https://cwe.mitre.org/data/definitions/492.html
References
- https://github.com/juliangruber/brace-expansion/commit/139d015104e71433ad52a41d19467c48ecbb2c7d
- https://github.com/juliangruber/brace-expansion/commit/1e30c930238d7162802d88a94189182def178dac
- https://github.com/juliangruber/brace-expansion/commit/688a99eeaab02627c2b89ba8ba4821fecfa659cf
- https://github.com/juliangruber/brace-expansion/commit/cb4b9e47cc2ec777c14b2b4492fb431a56f6a031
- https://github.com/juliangruber/brace-expansion/security/advisories/GHSA-rgw5-rvv9-x895
- https://github.com/juliangruber/brace-expansion/security/advisories/GHSA-rgw5-rvv9-x895