An IMAP FETCH response line indicates the size of the returned data, in number of bytes. When that response says the data is zero bytes, libcurl would pass on that (non-existing) data with a pointer and the size (zero) to the deliver-data function. libcurl's deliver-data function treats zero as a magic number and invokes strlen() on the data to figure out the length. The strlen() is called on a heap based buffer that might not be zero terminated so libcurl might read beyond the end of it into whatever memory lies after (or just crash) and then deliver that to the application as if it was actually downloaded.
This vulnerability carries a CRITICAL severity rating with a CVSS v3.1 score of 9.1, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), and availability (service disruption) for affected systems. Impacting 2 products from haxx, from debian organizations running these solutions should prioritize assessment and patching.
First disclosed in 2017, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.
2017-10-31T21:29:00.203
2025-04-20T01:37:25.860
Deferred
CVSSv3.0: 9.1 (CRITICAL)
AV:N/AC:L/Au:N/C:P/I:N/A:P
10.0
4.9
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | haxx | libcurl | ≤ 7.56.0 | Yes |
| Operating System | debian | debian_linux | 8.0 | Yes |
| Operating System | debian | debian_linux | 9.0 | Yes |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For haxx's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.