Inefficient Algorithmic Complexity Affecting bandit package, versions >=1.0.0-pre.7 <1.14.0
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
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.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-HEX-BANDIT-21755426
- published27 Oct 2026
- disclosed26 Oct 2026
- creditPeter Ullrich
Introduced: 26 Oct 2026
NewCVE-2026-113436 (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 Inefficient Algorithmic Complexity via parse_content_length in lib/bandit/headers.ex, which delegates to Integer.parse/1 for parsing numeric header values. An unauthenticated attacker can send HTTP/2 HEADERS frames carrying a content-length value composed of thousands of digit characters, causing Integer.parse/1 to consume CPU time grossly disproportionate to the size of the traffic sent, resulting in a server-side CPU exhaustion crash.
PoC
1. Run Bandit with any Plug.
2. Open an HTTP/2 connection with prior knowledge and complete the SETTINGS exchange.
3. In one write, send 5,000 HEADERS frames for `POST /` on new streams, each carrying a `content-length` of 4,000 `9` digits encoded with HPACK indexing, so that every frame after the first refers to the stored value.
4. The 124,003 bytes take 27.9 s to process before all 5,000 requests reach the Plug.
Note: The PoC states no specific environment, operating system, or non-default configuration.