CVE-2023-52628 in Linux
Summary
by MITRE • 03/28/2024
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nftables: exthdr: fix 4-byte stack OOB write
If priv->len is a multiple of 4, then dst[len / 4] can write past
the destination array which leads to stack corruption.
This construct is necessary to clean the remainder of the register in case ->len is NOT a multiple of the register size, so make it conditional just like nft_payload.c does.
The bug was added in 4.1 cycle and then copied/inherited when tcp/sctp and ip option support was added.
Bug reported by Zero Day Initiative project (ZDI-CAN-21950, ZDI-CAN-21951, ZDI-CAN-21961).
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Analysis
by VulDB Data Team • 03/17/2025
The vulnerability identified as CVE-2023-52628 represents a critical stack buffer overflow flaw within the Linux kernel's netfilter subsystem, specifically affecting the nftables implementation. This issue resides in the exthdr handling functionality where improper boundary checking leads to out-of-bounds memory writes. The flaw manifests when processing network packet headers through the nftables framework, creating a potential avenue for privilege escalation and system compromise. The vulnerability affects systems running Linux kernel versions from the 4.1 cycle onwards, making it a long-standing issue that has persisted through multiple kernel releases. The root cause stems from an inadequate boundary check in the packet header processing logic, where the code assumes that the length parameter will always align properly with memory register boundaries.
The technical implementation of this vulnerability occurs in the exthdr processing code where a conditional logic error allows for stack corruption. When the priv->len parameter is a multiple of four bytes, the code executes a write operation to dst[len / 4] that extends beyond the allocated destination array boundaries. This specific memory access pattern creates a four-byte stack overflow condition that can overwrite adjacent memory locations on the stack. The flaw operates through a fundamental misalignment between expected memory layout and actual execution flow, where the code path designed to handle remainder bytes in register cleanup inadvertently accesses memory beyond its intended boundaries. This issue was introduced during the kernel 4.1 development cycle and subsequently propagated when additional protocol support was added for tcp, sctp, and ip options, demonstrating how security flaws can persist across kernel version updates through code inheritance patterns.
The operational impact of this vulnerability extends beyond simple memory corruption, potentially enabling attackers to execute arbitrary code with kernel privileges or cause system crashes and denial of service conditions. The stack corruption could allow for privilege escalation attacks, where malicious actors leverage the overflow to gain elevated system access and potentially compromise the entire kernel runtime environment. The vulnerability's exploitation requires a specific set of conditions involving packet processing through nftables with particular header configurations, but once triggered, the consequences can be severe for network security and system stability. The flaw affects systems heavily reliant on netfilter and nftables for packet filtering and network address translation, making it particularly dangerous in enterprise and server environments where these kernel components are extensively used.
Mitigation strategies for CVE-2023-52628 focus on both immediate patch application and system hardening measures. Kernel updates addressing this vulnerability should be applied immediately to all affected systems, as the patch corrects the boundary checking logic to properly handle cases where length parameters are multiples of four bytes. The fix implements conditional logic similar to that used in nft_payload.c, ensuring that cleanup operations only execute when necessary and that memory boundaries are properly respected. System administrators should also implement network segmentation and monitoring to detect potential exploitation attempts, as this vulnerability may be used in combination with other attack vectors. The flaw's classification under CWE-121 heap-based buffer overflow and its potential mapping to ATT&CK technique T1068 for privilege escalation underscores the importance of comprehensive security measures. Organizations should conduct thorough vulnerability assessments to identify systems running affected kernel versions and prioritize patch deployment based on risk exposure levels. Additionally, implementing runtime protections such as stack canaries and address space layout randomization can provide additional defense-in-depth measures against potential exploitation attempts.