It was found that xorg-x11-server before 1.19.0 including uses memcmp() to check the received MIT cookie against a series of valid cookies. If the cookie is correct, it is allowed to attach to the Xorg session. Since most memcmp() implementations return after an invalid byte is seen, this causes a time difference between a valid and invalid byte, which could allow an efficient brute force attack.
This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 5.9, requiring local system access to exploit but requires specific conditions to be met without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), for affected systems. Impacting 2 products from x.org, from debian organizations running these solutions should prioritize assessment and patching.
First disclosed in 2018, 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.
2018-07-27T18:29:00.827
2025-08-29T13:42:30.557
Modified
CVSSv3.0: 5.9 (MEDIUM)
AV:L/AC:M/Au:N/C:P/I:N/A:N
3.4
2.9
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | x.org | x_server | ≤ 1.19.4 | Yes |
| Operating System | debian | debian_linux | 7.0 | 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 x.org'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.