High [CVE-2026-14257 +1] DoS via unbounded intermediate arrays, bypassing the CVE-2026-14257 mitigation

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.

This issue is due to an incomplete mitigation of CVE-2026-14257. Any applications that pass user-controlled input to the `expand()` function are vulnerable to this issue.

This flaw can result in an excessive consumption of memory that eventually terminates the process or blocks the event loop, both causing a denial of service. As this vulnerability allows a remote attacker to cause a denial of service, it has been rated with an important severity.

Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-770.

Affected products named by the advisory: Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.6 Extended Update Support; Red Hat Advanced Cluster Security 4.9; and 49 more.