CVE-2026-113436
Quadratic bignum parsing of Content-Length and Host port values in Bandit
- State
- Published
- Severity
- 8.7 High
- Published
- Oct 26, 2026
- Updated
- Oct 26, 2026
- Reserved
- Oct 23, 2026
Description
Inefficient Algorithmic Complexity vulnerability in the header integer parser of mtrudel bandit allows an unauthenticated remote attacker to consume server CPU via a content-length value or a Host or :authority port made of thousands of digits.
Bandit.Headers.parse_integer/2 in lib/bandit/headers.ex builds the number one digit at a time with no limit on the digit count, allocating a new bignum at each step, so one value costs time quadratic in its length. It runs on raw request input over HTTP/1 and HTTP/2, before any range check. Over HTTP/2, a 4,000-digit value can be stored once in the HPACK dynamic table and re-sent on each new stream for about one byte: 124 KB of traffic kept the server busy for 27.9 s.
This issue affects bandit: from 1.0.0-pre.7 before 1.14.0.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | EEF |
Weaknesses
- CWE-407 Inefficient Algorithmic Complexity
Affected Products
| Product | Versions |
|---|---|
banditmtrudel |
|
banditmtrudel |
|
References
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