Improper Handling of Highly Compressed Data (Data Amplification) Affecting bandit package, versions >=0.3.3 <1.14.0
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-HEX-BANDIT-21755472
- published27 Oct 2026
- disclosed26 Oct 2026
- creditUnknown
Introduced: 26 Oct 2026
NewCVE-2026-109584 (opens in a new tab)How to fix?
Upgrade bandit to version 1.14.0 or higher.
Overview
bandit is a HTTP server for Plug and WebSock apps.
Affected versions of this package are vulnerable to Improper Handling of Highly Compressed Data (Data Amplification) via the HTTP/2 implementation of mtrudel bandit allows an unauthenticated remote attacker to exhaust server memory via a small HPACK-compressed HEADERS block. The attack defines a large cookie value in the HPACK dynamic table and repeatedly references it using 1-byte indices. Because max_header_list_size defaults to :infinity, Bandit enforces no size cap on the decompressed headers; combine_cookie_crumbs/1 then concatenates all instances into an enormous binary. A 49 KB payload can force a 183 MB memory allocation before application logic executes, enabling concurrent streams to rapidly exhaust server memory.