The Linux kernel version 3.3-rc1 and later is affected by a vulnerability lies in the processing of incoming L2CAP commands - ConfigRequest, and ConfigResponse messages. This info leak is a result of uninitialized stack variables that may be returned to an attacker in their uninitialized state. By manipulating the code flows that precede the handling of these configuration messages, an attacker can also gain some control over which data will be held in the uninitialized stack variables. This can allow him to bypass KASLR, and stack canaries protection - as both pointers and stack canaries may be leaked in this manner. Combining this vulnerability (for example) with the previously disclosed RCE vulnerability in L2CAP configuration parsing (CVE-2017-1000251) may allow an attacker to exploit the RCE against kernels which were built with the above mitigations. These are the specifics of this vulnerability: In the function l2cap_parse_conf_rsp and in the function l2cap_parse_conf_req the following variable is declared without initialization: struct l2cap_conf_efs efs; In addition, when parsing input configuration parameters in both of these functions, the switch case for handling EFS elements may skip the memcpy call that will write to the efs variable: ... case L2CAP_CONF_EFS: if (olen == sizeof(efs)) memcpy(&efs, (void *)val, olen); ... The olen in the above if is attacker controlled, and regardless of that if, in both of these functions the efs variable would eventually be added to the outgoing configuration request that is being built: l2cap_add_conf_opt(&ptr, L2CAP_CONF_EFS, sizeof(efs), (unsigned long) &efs); So by sending a configuration request, or response, that contains an L2CAP_CONF_EFS element, but with an element length that is not sizeof(efs) - the memcpy to the uninitialized efs variable can be avoided, and the uninitialized variable would be returned to the attacker (16 bytes).
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 4.15-rc4 | 4.15-rc4.x |
| linux / linux_kernel | 4.15-rc1 | 4.15-rc1.x |
| linux / linux_kernel | 4.15-rc2 | 4.15-rc2.x |
| linux / linux_kernel | 4.15-rc3 | 4.15-rc3.x |
| linux / linux_kernel | 4.15-rc7 | 4.15-rc7.x |
| linux / linux_kernel | 4.15-rc6 | 4.15-rc6.x |
| linux / linux_kernel | 4.15-rc5 | 4.15-rc5.x |
| linux / linux_kernel | 3.2.x | 4.15 |
| debian / debian_linux | 8.0 | 8.0.x |
| debian / debian_linux | 9.0 | 9.0.x |
| redhat / enterprise_linux_desktop | 7.0 | 7.0.x |
| redhat / enterprise_linux_workstation | 7.0 | 7.0.x |
| redhat / enterprise_linux_server | 7.0 | 7.0.x |
| redhat / enterprise_linux_desktop | 6.0 | 6.0.x |
| redhat / enterprise_linux_server | 6.0 | 6.0.x |
| redhat / enterprise_linux_workstation | 6.0 | 6.0.x |
| redhat / enterprise_linux_server_eus | 7.4 | 7.4.x |
| redhat / virtualization_host | 4.0 | 4.0.x |
| redhat / enterprise_linux_server_tus | 7.4 | 7.4.x |
| redhat / enterprise_linux_server_tus | 7.6 | 7.6.x |
| redhat / enterprise_linux_server_eus | 7.6 | 7.6.x |
| redhat / enterprise_linux_server_aus | 7.6 | 7.6.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.