mtrudel bandit up to 1.13.9 Header Integer Parser lib/bandit/headers.ex Bandit.Headers.parse_integer content-length resource consumption

Summaryinfo

A vulnerability was found in mtrudel bandit up to 1.13.9. It has been declared as problematic. This impacts the function Bandit.Headers.parse_integer of the file lib/bandit/headers.ex of the component Header Integer Parser. Such manipulation of the argument content-length leads to resource consumption. This vulnerability is documented as CVE-2026-113436. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in mtrudel bandit up to 1.13.9. It has been rated as problematic. Affected by this issue is the function Bandit.Headers.parse_integer of the file lib/bandit/headers.ex of the component Header Integer Parser. The manipulation of the argument content-length with an unknown input leads to a resource consumption vulnerability. Using CWE to declare the problem leads to CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. Impacted is availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-113436 since 10/23/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 1.14.0 eliminates this vulnerability.

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Productinfo

Vendor

• mtrudel

Name

• bandit

Version

• 1.13.0
• 1.13.1
• 1.13.2
• 1.13.3
• 1.13.4
• 1.13.5
• 1.13.6
• 1.13.7
• 1.13.8
• 1.13.9

Website

• Product: https://github.com/mtrudel/bandit/

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