Description

Dell Client BIOS contains an Improper Link Resolution Before File Access ('Link Following') vulnerability. A low privileged attacker with local access could potentially exploit this vulnerability, leading to Arbitrary Write

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.6",
  "pubDate": "2026-08-24T20:16:55.677Z",
  "pubdate": "2026-08-24T20:16:55.677Z",
  "executiveSummary": "A vulnerability has been identified within Dell Client BIOS involving improper link resolution before file access, commonly classified as link following. This security flaw arises when the software fails to properly validate and resolve symbolic links or hard links before performing file system operations, allowing interactions with unintended target files.\nThe primary security impact of this vulnerability is arbitrary write capability. Successful exploitation of this flaw could allow an attacker to overwrite critical system files, modify configuration data, or potentially manipulate firmware or operating system components residing on the underlying storage media.\nThe affected product line is Dell Client BIOS. The risk implications are severe due to the low-level execution context of the BIOS environment, where unauthorized modifications can compromise the entire platform integrity and underlying operating system security controls.\nTo successfully execute an exploit against this vulnerability, an attacker must possess local access to the target endpoint. Furthermore, exploitation requires low-privileged access to the system, meaning an authenticated user or a localized malicious process with minimal permissions can potentially leverage the flaw to escalate privileges or inflict persistent system damage.",
  "technicalDetails": "The root cause of the vulnerability stems from an Improper Link Resolution Before File Access ('Link Following') flaw within the Dell Client BIOS file handling routines. When the BIOS or associated low-level utilities process file read, write, or access operations, the code fails to adequately check whether the target path points to a symbolic link, junction point, or hard link pointing outside the intended secure directory structure.\nThe vulnerable component resides within the Dell Client BIOS subsystem responsible for managing localized file persistence, logging, or update mechanisms that interact with the underlying file system. Because this routine blindly follows links without sufficient validation, it becomes susceptible to race conditions or deterministic link redirection.\nRegarding authentication and privilege requirements, the attack requires local access to the targeted machine. The attacker must possess low privileges on the system to stage the necessary file system structures, such as symbolic links, prior to triggering the vulnerable BIOS operation. The vulnerability does not require network exposure, as it cannot be remotely triggered over a network interface without prior local execution capability.\nThe step-by-step attack flow proceeds as follows: First, the low-privileged attacker identifies a file operation performed by the Dell Client BIOS that interacts with a predictable file path or location within the file system. Second, the attacker establishes a symbolic link or junction at that expected location, pointing the path toward a critical, highly sensitive system file that the attacker normally lacks direct permission to modify. Third, the attacker initiates or waits for the BIOS routine to execute, which subsequently follows the link during the file access phase without verifying the link destination. Finally, the BIOS performs the write operation, resulting in arbitrary write primitives against the sensitive target file designated by the attacker.\nThe post-exploitation impact of achieving arbitrary write within the context of system BIOS interactions includes system instability, corruption of boot-critical components, persistence mechanisms, and potential escalation of privilege leading to complete compromise of the host operating system."
}