Description

A path traversal vulnerability in LXD allows an attacker to manipulate file system paths during backup import and restore operations. When importing or restoring a backup archive, LXD fails to validate instance and storage volume names contained within the archive metadata. An attacker can exploit this flaw by supplying a crafted backup archive with malicious instance or volume names containing path traversal sequences, potentially allowing file access or overwriting outside the designated restore directory.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.9",
  "pubDate": "2026-08-12T21:17:39.700Z",
  "pubdate": "2026-08-12T21:17:39.700Z",
  "executiveSummary": "A path traversal vulnerability has been identified in LXD, specifically residing within the backup import and restore functional components of the product. The core issue stems from an inadequate validation mechanism for instance and storage volume names embedded within the metadata of backup archives. By exploiting this flaw, a remote or local attacker possessing the capability to supply a crafted backup archive can manipulate file system paths during the import and restore processes.\nThe primary impact of this vulnerability involves unauthorized file access and the potential capability to overwrite critical files residing outside the designated restore directory boundaries. This compromises the integrity and confidentiality of the host file system. The attack requires the targeted system to process a maliciously crafted backup archive containing directory traversal sequences within its metadata structure. Consequently, risk implications are elevated for environments where untrusted backup archives are routinely imported or restored, potentially leading to privilege escalation or arbitrary file manipulation depending on the privileges of the LXD daemon.",
  "technicalDetails": "The vulnerability is classified as a path traversal flaw affecting the backup handling routines of LXD. The root cause of the vulnerability is the absence of rigorous input sanitization and validation checks on instance and storage volume names extracted from the metadata of incoming backup archives. When LXD parses these archives during import or restore operations, it fails to neutralize relative path traversal sequences such as dot-dot-slash (../) embedded in the malicious names.\nThe exploitation method relies on the supply of a specially crafted backup archive. An attacker crafts an archive where the internal metadata specifies instance or volume identifiers containing malicious path traversal sequences. Upon processing this archive, the vulnerable component attempts to construct file system paths using these unsanitized identifiers. Because input validation is lacking, the resulting file path resolves to directories outside the intended sandbox or designated restore root.\nThe attack flow proceeds in sequential phases. First, the attacker generates or modifies a backup archive to include path traversal payloads in the metadata defining instance or storage volume names. Second, the attacker initiates a backup import or restore operation through the LXD interface. Third, the LXD daemon processes the archive, reads the malicious metadata, and constructs destination paths that traverse upwards in the directory tree. Finally, during the write operations of the restore process, data is read from or written to arbitrary locations on the host file system, enabling file overwrite or unauthorized access.\nThe vulnerable component comprises the backup import and restore subsystems responsible for parsing archive metadata and materializing instances and storage volumes. While specific version numbers and authentication or privilege requirements are not exhaustively detailed in the baseline description, typical exploitation of backup import mechanisms assumes an attacker has sufficient privileges to initiate a restore operation or interact with the LXD API to supply the malicious payload. Post-exploitation impact includes the modification or corruption of system configuration files, unauthorized disclosure of sensitive data, or potential execution of further compromise vectors if critical binaries or startup scripts are overwritten."
}