Vulnerability details

Allocation of Resources Without Limits or Throttling vulnerability in the WebSocket fragment reassembly of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via a fragmented message made of many 1-byte continuation frames. Bandit.WebSocket.Connection checks max_fragmented_message_size against the payload bytes received, but keeps every non-final continuation frame as a new list cell around its own binary, and nothing limits the number of fragments. A 1-byte fragment costs 7 bytes on the wire but about 150 to 170 bytes of server memory, so one connection can hold about 150 times the configured limit, roughly 1.2 to 1.4 GB at the default 8 MB. Ping frames between fragments keep the connection alive past the idle timeout. This issue affects bandit: from 1.11.0 before 1.14.0.

• https://github.com/mtrudel/bandit/security/advisories/GHSA-cpx7-qf6w-jc63 vendor-advisoryrelated
• https://cna.erlef.org/cves/CVE-2026-114213.html related
• https://osv.dev/vulnerability/EEF-CVE-2026-114213 related
• https://github.com/mtrudel/bandit/commit/21612c7c7b1ce43eccd36d3af3a2299d23513667 related
• https://github.com/mtrudel/bandit/commit/220b9dfd27f9a21305be2afc75cbe585ddc24e7a patch