CVE-2022-32206 is a vulnerability identified in the curl library versions prior to 7.84.0, related to the handling of HTTP response compression. Curl supports "chained" HTTP compression algorithms, where a server response can be compressed multiple times using different algorithms in sequence. The vulnerability arises because the number of compression layers (or "links" in the decompression chain) was unbounded, allowing a malicious server to craft a response with an excessively long chain of compressed data. When curl attempts to decompress such a response, it can lead to a "malloc bomb" scenario, where the library allocates an enormous amount of heap memory to handle the decompression steps. This can cause curl to consume excessive memory resources, potentially leading to out-of-memory errors or crashes. The vulnerability is classified under CWE-770 (Allocation of Resources Without Limits or Throttling), indicating that the software does not impose limits on resource consumption, which can be exploited to cause denial of service (DoS). The CVSS v3.1 score is 6.5 (medium severity), with the vector indicating that the attack can be performed remotely without privileges (AV:N/AC:L/PR:N), requires user interaction (UI:R), and impacts availability (A:H) but not confidentiality or integrity. No known exploits are reported in the wild. The issue was fixed in curl version 7.84.0 by introducing limits on the decompression chain length to prevent excessive resource allocation.

For European organizations, this vulnerability poses a risk primarily of denial of service. Applications and services that rely on curl for HTTP communications and that process responses from potentially untrusted or external servers could be targeted by attackers who craft malicious HTTP responses with deeply nested compression chains. This can cause the affected curl client to consume excessive memory, leading to application crashes or degraded performance. Such disruptions can impact web clients, automated scripts, CI/CD pipelines, or any system component using vulnerable curl versions. While the vulnerability does not directly compromise confidentiality or integrity, the availability impact can affect business operations, especially for organizations with high dependency on automated data retrieval or API integrations. The risk is heightened in environments where user interaction triggers curl requests to external servers, such as browsers or client applications fetching remote content. Since no authentication or privileges are required for exploitation, and the attack vector is network-based, the threat can be exploited remotely. European organizations should be aware that this vulnerability could be leveraged in targeted DoS attacks or as part of multi-stage attacks aiming to disrupt services.

To mitigate this vulnerability, European organizations should ensure that all instances of curl are updated to version 7.84.0 or later, where the decompression chain length is properly limited. For environments where immediate patching is not feasible, consider implementing network-level controls such as web application firewalls (WAFs) or intrusion prevention systems (IPS) that can detect and block suspicious HTTP responses with abnormal compression headers or unusually large payloads. Application developers should audit their use of curl to confirm that it is not exposed to untrusted servers without validation. Additionally, monitoring memory usage and application logs for signs of abnormal resource consumption related to HTTP decompression can provide early detection of exploitation attempts. Organizations should also review and restrict user interactions that trigger curl requests to untrusted endpoints. Finally, incorporating security testing that simulates malicious compression chains can help validate the robustness of curl usage in internal applications.