elixir-mint up to 1.8.x request.ex Target crlf injection

Summaryinfo

A vulnerability has been found in elixir-mint mint up to 1.8.x and classified as critical. Affected is an unknown function in the library lib/mint/http1/request.ex. This manipulation of the argument Target causes crlf injection. This vulnerability appears as CVE-2026-48861. The attack requires local access. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in elixir-mint mint up to 1.8.x. Affected by this vulnerability is an unknown part in the library lib/mint/http1/request.ex. The manipulation of the argument target with an unknown input leads to a crlf injection vulnerability. The CWE definition for the vulnerability is CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in elixir-mint Mint allows HTTP Request Splitting and HTTP Request Smuggling. In lib/mint/http1/request.ex, the encode_request_line/2 function splices the caller-supplied method and target arguments directly into the HTTP/1 request line without any character validation: [method, ?\s, target, " HTTP/1.1\r\n"]. An application that forwards attacker-controlled input as the HTTP method or target to Mint.HTTP.request/5 is therefore exposed to request-line CRLF injection: the attacker can terminate the request line early, inject arbitrary headers, and smuggle an entirely separate pipelined HTTP request onto the same TCP connection. Mint 1.7.0 introduced validate_request_target/2, which rejects CRLF and other control characters in the target by default and closes the path/query vector unless the caller opts out via skip_target_validation: true. The method field remains unvalidated, so the method-based injection is exploitable under the default Mint configuration on all versions. This issue affects mint: from 0.1.0 before 1.9.0.

The weakness was presented by Peter Ullrich and Jonatan Männchen as GHSA-2pg6-44cx-c49v. The advisory is shared at github.com. This vulnerability is known as CVE-2026-48861 since 05/25/2026. The exploitation appears to be easy. An attack has to be approached locally. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available.

Upgrading to version 1.9.0 eliminates this vulnerability. Applying the patch fad091454cbb7449b19edb8e1fee12ca7cf28c3a is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-33938). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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

License

• open-source

Website

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

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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