---
id: "CVE-2026-115269"
kind: "vulnerability"
aliases: ["CVE-2026-115269"]
title: "Bandit: HTTP/2 frames let a client hold request streams open indefinitely"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["bandit", "elixir", "http2", "package", "phoenix", "plug", "self-hosted"]
not_affected_if: ["bandit-below-1.4.0-or-1.14.0-plus", "http1-only", "http2-terminated-at-proxy"]
published_at: "2026-10-26T14:16:31+00:00"
first_seen_at: "2026-10-26T14:30:36+00:00"
updated_at: "2026-10-26T14:32:07+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-115269", "first_seen_at": "2026-10-26T14:30:36+00:00"}]
---

# Bandit: HTTP/2 frames let a client hold request streams open indefinitely

Bandit is an Elixir HTTP server. A remote client can send repeated WINDOW_UPDATE or empty SETTINGS frames while an application reads a request body, resetting the read timeout each time so the stream process stays blocked indefinitely.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Bandit version in `mix.lock` or `mix deps` output for `bandit`
- Confirm whether the app serves HTTP/2 through Bandit (e.g., `:bandit` listener with HTTP/2 enabled)

## Fix

- Upgrade `bandit` to `1.14.0` or later

## Timeline

- 2026-10-26T14:30:36+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-115269

## From the sources

Allocation of Resources Without Limits or Throttling vulnerability in the HTTP/2 request body reader of mtrudel bandit allows an unauthenticated remote attacker to hold stream processes open indefinitely via WINDOW_UPDATE or empty SETTINGS frames sent while a Plug reads the request body.

Bandit.HTTP2.Stream.do_read_data/4 in lib/bandit/http2/stream.ex waits for each frame with a fresh read_timeout. A stream WINDOW_UPDATE, or the zero-delta window update that every empty SETTINGS frame delivers to all streams, ends the wait without delivering any body data, and the loop starts a new full countdown. A client that sends one of these 9-byte frames before each countdown expires keeps read_body blocked, together with the stream process and whatever the application holds while reading, for as long as it likes.

This issue affects bandit: from 1.4.0 before 1.14.0.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_