benoitc hackney up to 4.0.0 URL Parser src/hackney_url.erl allocation of resources

Summaryinfo

A vulnerability identified as problematic has been detected in benoitc hackney up to 4.0.0. Affected is an unknown function of the file src/hackney_url.erl of the component URL Parser. The manipulation leads to allocation of resources. This vulnerability is uniquely identified as CVE-2026-47067. The attack is possible to be carried out remotely. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in benoitc hackney up to 4.0.0. It has been rated as problematic. This issue affects some unknown functionality of the file src/hackney_url.erl of the component URL Parser. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to 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. Impacted is availability. The summary by CVE is:

Allocation of Resources Without Limits or Throttling vulnerability in benoitc hackney allows Flooding. The URL parser in src/hackney_url.erl converts every unrecognized URL scheme to a permanent BEAM atom via binary_to_atom/2. BEAM atoms are never garbage-collected and the atom table defaults to a hard limit of 1,048,576 entries. An attacker who can supply URLs with attacker-chosen scheme prefixes — directly as request targets, as configured webhook URLs, or via Location headers followed during redirects — can exhaust the atom table and crash the entire BEAM VM with system_limit. This issue affects hackney: from 2.0.0 before 4.0.1.

The weakness was disclosed by Peter Ullrich and Jonatan Männchen. It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-47067 since 05/18/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 4.0.1 eliminates this vulnerability. Applying the patch 31f6f0e27e096ad88743dfded4f030a3ee74972e is able to eliminate this problem. 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-2026-31691). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

• benoitc

Name

• hackney

Version

• 4.0

Website

• Product: https://github.com/benoitc/hackney/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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