CVE-2026-113436 Quadratic bignum parsing of Content-Length and Host port values in Bandit
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-113436?
CVE-2026-113436 is a high-severity vulnerability in mtrudel bandit, published on 26 Oct 2026.
Official 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.
Weakness: CWE-407
Which versions are affected by CVE-2026-113436?
1 open source package ship an affected version, including bandit.
| Package | Affected | Fixed in |
|---|---|---|
bandit Hex | From 1.0.0-pre.7 | 1.14.0 |
How do I fix CVE-2026-113436?
Upgrade bandit to 1.14.0 or later.
Is CVE-2026-113436 being exploited?
There is no known exploitation of CVE-2026-113436 in the wild and no public exploit code.
Sources
Also known as EEF-CVE-2026-113436, GHSA-29cr-8477-rg6r, UBUNTU-CVE-2026-113436.