CVE-2026-33750

The brace-expansion library generates arbitrary strings containing a common prefix and suffix. Prior to versions 5.0.5, 3.0.2, 2.0.3, and 1.1.13, a brace pattern with a zero step value (e.g., {1..2..0}) causes the sequence generation loop to run indefinitely, making the process hang for seconds and allocate heaps of memory. Versions 5.0.5, 3.0.2, 2.0.3, and 1.1.13 fix the issue. As a workaround, sanitize strings passed to expand() to ensure a step value of 0 is not used.

Weakness

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

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/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L107-L113
• https://github.com/juliangruber/brace-expansion/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L184
• https://github.com/juliangruber/brace-expansion/commit/311ac0d54994158c0a384e286a7d6cbb17ee8ed5
• https://github.com/juliangruber/brace-expansion/commit/7fd684f89fdde3549563d0a6522226a9189472a2
• https://github.com/juliangruber/brace-expansion/commit/b9cacd9e55e7a1fa588fe4b7bb1159d52f1d902a
• https://github.com/juliangruber/brace-expansion/issues/98
• https://github.com/juliangruber/brace-expansion/pull/95
• https://github.com/juliangruber/brace-expansion/pull/96
• https://github.com/juliangruber/brace-expansion/pull/97
• https://github.com/juliangruber/brace-expansion/security/advisories/GHSA-f886-m6hf-6m8v