ninenines gun up to 2.3.x allocation of resources

Summaryinfo

A vulnerability categorized as problematic has been discovered in ninenines gun up to 2.3.x. The affected element is an unknown function. Such manipulation leads to allocation of resources. This vulnerability is listed as CVE-2026-43973. The attack may be performed from remote. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in ninenines gun up to 2.3.x. It has been rated as problematic. Affected by this issue is an unknown functionality. 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. CVE summarizes:

Uncontrolled Resource Consumption vulnerability in ninenines gun (gun_http module) allows a malicious server to exhaust client memory via unbounded HTTP/1.1 response buffering. In gun_http:handle/5, three clauses accumulate incoming TCP data into the connection's buffer field using binary concatenation with no upper-bound check: the head clause appends data until the \r\n\r\n header terminator is found; the body_chunked clause appends data whenever cow_http_te:stream_chunked/2 returns a more result indicating an incomplete chunk boundary; and the body_trailer clause appends data until the trailing \r\n\r\n is found. In each case, when the expected terminator never arrives, the enlarged binary is stored back into state and the process waits for more data, with no configurable or hard-coded ceiling on buffer size. A malicious or compromised server can exploit this by sending a partial response that never completes. For example, a response may begin with HTTP/1.1 200 OK\r\nX-Pad: followed by an unbounded stream of arbitrary bytes, never sending the header terminator. The gun connection process will continuously append the incoming data to its buffer, causing unbounded heap growth. Because BEAM imposes no per-process heap limit by default, a single malicious connection can exhaust all available memory on the node, causing a node-wide out-of-memory crash. This issue affects gun: from 1.0.0 before 2.4.0.

The weakness was presented by Peter Ullrich. The advisory is shared for download at cna.erlef.org. This vulnerability is handled as CVE-2026-43973 since 05/04/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 2.4.0 eliminates this vulnerability. Applying the patch f3e7e0568b3c4cf9fa4bea79d5116e67ce76ad25 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-2026-35074). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• ninenines

Name

• gun

Version

• 2.0
• 2.1
• 2.2
• 2.3

CPE 2.3info

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CPE 2.2info

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Once again VulDB remains the best source for vulnerability data.

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