CVE-2026-23112 in Linux
Summary
by MITRE • 02/13/2026
In the Linux kernel, the following vulnerability has been resolved:
nvmet-tcp: add bounds checks in nvmet_tcp_build_pdu_iovec
nvmet_tcp_build_pdu_iovec() could walk past cmd->req.sg when a PDU length or offset exceeds sg_cnt and then use bogus sg->length/offset values, leading to _copy_to_iter() GPF/KASAN. Guard sg_idx, remaining entries, and sg->length/offset before building the bvec.
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Analysis
by VulDB Data Team • 05/06/2026
The vulnerability identified as CVE-2026-23112 resides within the Linux kernel's nvme over tcp subsystem, specifically in the nvmet_tcp_build_pdu_iovec function. This issue represents a classic buffer overflow condition that can lead to system instability and potential privilege escalation. The vulnerability affects the NVMe over TCP target implementation which handles network communication for non-volatile memory express storage devices. The flaw occurs when processing Protocol Data Units (PDUs) that exceed the bounds of the scatter-gather list entries, creating a scenario where the kernel attempts to access memory locations beyond the allocated buffer space. This particular vulnerability demonstrates a failure in proper input validation and memory boundary checking within kernel space networking code.
The technical implementation of this vulnerability stems from insufficient bounds checking within the nvmet_tcp_build_pdu_iovec function. When processing incoming PDU data, the function fails to validate that the specified PDU length or offset values do not exceed the available scatter-gather entries. This oversight allows for a situation where the code iterates beyond the legitimate command request scatter-gather array boundaries, subsequently referencing invalid memory locations. The function operates by building a vector of scatter-gather entries to facilitate data transfer operations, but without proper validation of indices and lengths, it can access memory that has not been properly allocated or initialized. This condition directly violates the principles of safe memory access and can result in kernel page faults or kernel address sanitizer (KASAN) detection. The vulnerability manifests as a potential null pointer dereference or access to freed memory locations, which are common indicators of buffer overflow conditions.
The operational impact of this vulnerability extends beyond simple system instability, potentially enabling attackers to execute arbitrary code within kernel space or cause denial of service conditions. When the kernel encounters invalid scatter-gather entries, it may trigger a general protection fault (GPF) or KASAN report, effectively crashing the system or allowing for privilege escalation. The vulnerability affects systems running Linux kernel versions that include the nvme over tcp target functionality, particularly those implementing network storage solutions using NVMe protocols. Attackers could exploit this by crafting malicious PDU packets with oversized length or offset values, causing the kernel to traverse invalid memory regions and potentially execute unintended code paths. The attack surface is primarily limited to systems serving NVMe over TCP targets, but the implications are severe given that kernel-level vulnerabilities can compromise entire system operations. This vulnerability aligns with CWE-129 Input Validation and CWE-787 Out-of-bounds Write categories, representing a failure in proper bounds checking and input sanitization.
Mitigation strategies for CVE-2026-23112 should focus on implementing robust bounds checking and memory validation procedures within the kernel networking subsystem. The most effective approach involves applying the upstream kernel patch that introduces proper validation of scatter-gather indices, remaining entry counts, and scatter-gather entry lengths before processing data. System administrators should prioritize updating their kernel versions to include the patched implementation, which typically involves verifying that sg_idx values do not exceed sg_cnt limits and that individual scatter-gather entry lengths and offsets are properly validated. Organizations should also consider implementing network segmentation and monitoring to detect anomalous PDU patterns that might indicate exploitation attempts. The solution aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, as the vulnerability enables potential code execution through network-based attacks. Regular kernel security updates and vulnerability assessments should be implemented as part of comprehensive security operations, with particular attention to network-facing kernel components. The fix demonstrates the importance of defensive programming practices in kernel space code, emphasizing the need for comprehensive input validation and boundary checking in all memory access operations.