elixir-mint up to 1.8.x conn.headers_being_processed peer-advertised allocation of resources

Summaryinfo

A vulnerability, which was classified as problematic, has been found in elixir-mint mint up to 1.8.x. Impacted is the function conn.headers_being_processed. Performing a manipulation of the argument peer-advertised results in allocation of resources. This vulnerability is reported as CVE-2026-49754. The attack is possible to be carried out remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in elixir-mint mint up to 1.8.x. This affects the function conn.headers_being_processed. The manipulation of the argument peer-advertised with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as 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. This is going to have an impact on availability. The summary by CVE is:

Allocation of Resources Without Limits or Throttling vulnerability in elixir-mint Mint allows attacker-controlled HTTP/2 servers to exhaust memory in a Mint client (HTTP/2 CONTINUATION flood). When Mint's HTTP/2 receive path observes a HEADERS frame without the END_HEADERS flag, the unparsed header-block fragment is parked in conn.headers_being_processed, and every subsequent CONTINUATION frame on that stream is appended to the accumulator. Nothing in the receive path caps the accumulator: there is no per-stream size limit, no CONTINUATION frame-count limit, and max_header_list_size is only enforced on outgoing requests, never on inbound header blocks (its default is :infinity). A malicious or compromised HTTP/2 server can stream an endless sequence of CONTINUATION frames (each up to the peer-advertised SETTINGS_MAX_FRAME_SIZE) and drive the client's iolist to arbitrary size, causing memory exhaustion and BEAM process death. A single connection to an attacker-controlled HTTP/2 endpoint is sufficient. This issue affects mint: from 0.1.0 before 1.9.0.

The weakness was disclosed by Peter Ullrich and Jonatan Männchen as GHSA-2p26-p43x-fhp8. The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-49754 since 06/01/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 1.9.0 eliminates this vulnerability. Applying the patch b662d127d3028b5426c88d4c9cc7fe430491a10b 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-2026-33940). 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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