Vulnerability Description
Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion. The fragment reassembly path in 'Elixir.Bandit.WebSocket.Connection':handle_frame/3 in lib/bandit/websocket/connection.ex appends every incoming Continuation{fin: false} frame's payload to a per-connection iolist with no cumulative size cap. The existing max_frame_size option only bounds individual frames; a peer that streams an unbounded number of continuation frames without ever setting fin=1 grows BEAM heap linearly until the OS or a supervisor kills the process. Because the accumulation happens before WebSock.handle_in/2 is called, the application has no opportunity to interpose a size check. Phoenix Channels and LiveView both run over WebSock on Bandit, so a stock Phoenix application exposes this surface as soon as it accepts socket connections. This issue affects bandit: from 0.5.0 before 1.11.0.
Related Weaknesses (CWE)
References
- https://cna.erlef.org/cves/CVE-2026-42786.html
- https://github.com/mtrudel/bandit/commit/21612c7c7b1ce43eccd36d3af3a2299d2351366
- https://github.com/mtrudel/bandit/security/advisories/GHSA-pf94-94m9-536p
- https://osv.dev/vulnerability/EEF-CVE-2026-42786
- https://github.com/mtrudel/bandit/security/advisories/GHSA-pf94-94m9-536p
FAQ
What is CVE-2026-42786?
CVE-2026-42786 is a documented vulnerability. Allocation of Resources Without Limits or Throttling vulnerability in mtrudel bandit allows unauthenticated remote denial of service via memory exhaustion. The fragment reassembly path in 'Elixir.Ban...
How severe is CVE-2026-42786?
CVSS scoring is not yet available for CVE-2026-42786. Check NVD for updates.
Is there a patch for CVE-2026-42786?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.