elixir-mint up to 1.9.x HTTP Parser lib/mint/http1/parse.ex parse_hex_prefix allocation of resources

Summaryinfo

A vulnerability, which was classified as problematic, was found in elixir-mint mint up to 1.9.x. Affected by this issue is the function parse_hex_prefix of the file lib/mint/http1/parse.ex of the component HTTP Parser. Executing a manipulation can lead to allocation of resources. This vulnerability is handled as CVE-2026-82729. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in elixir-mint mint up to 1.9.x. It has been declared as problematic. This vulnerability affects the function parse_hex_prefix of the file lib/mint/http1/parse.ex of the component HTTP Parser. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect availability. CVE summarizes:

Inefficient Algorithmic Complexity vulnerability in elixir-mint mint allows a remote HTTP server to exhaust CPU on the client host and cause a denial of service. parse_hex_prefix/2 in lib/mint/http1/parse.ex folds each hex digit of a chunked response's chunk-size field into an arbitrary-precision accumulator with acc * 16 + digit and imposes no limit on the digit count. Because the accumulator grows without bound, the multiplication is not constant time and one pass over N digits costs O(N squared). handle_data/2 prepends conn.buffer and re-parses from the start on every socket message, so a server that dribbles the digits out in small packets makes the client pay that cost repeatedly. A run of roughly 512,000 hex digits costs over ten seconds of CPU in a single pass, measured on stock defaults. The parser reaches this state after a valid status line and a complete, valid header section, so an intermediary inspecting only headers sees an ordinary 200 response. This issue affects mint: from 1.9.3 before 1.10.0.

The advisory is available at github.com. This vulnerability was named CVE-2026-82729 since 08/31/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful 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 1.10.0 eliminates this vulnerability.

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Productinfo

Vendor

• elixir-mint

Name

• mint

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9

Website

• Product: https://github.com/elixir-mint/mint/

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