CVE-2024-56433
Published: 26 December 2024
Summary
CVE-2024-56433 is a low-severity Initialization of a Resource with an Insecure Default (CWE-1188) vulnerability. Its CVSS base score is 3.6 (Low).
Operationally, ranked in the top 9.1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
Deeper analysis
The vulnerability CVE-2024-56433 affects shadow-utils (shadow) versions 4.4 through 4.17.0. It stems from the package's default /etc/subuid configuration, which assigns UID ranges such as 100000-165535 to the first local user account for user namespace mappings, creating a realistic overlap risk with UIDs already in use on locally administered networks.
A local user or remote login session can exploit the conflict by invoking newuidmap to map into the overlapping range, thereby obtaining access to an NFS home directory or other same-host resources owned by the network-defined accounts and achieving partial account takeover.
The referenced login.defs defaults and GitHub issue 1157 note that system administrators should avoid assigning local network UIDs inside the ranges that shadow may allocate in /etc/subuid.
EPSS remains flat at 0.06 with no material rise after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2024-53142
Vulnerability details
shadow-utils (aka shadow) 4.4 through 4.17.0 establishes a default /etc/subuid behavior (e.g., uid 100000 through 165535 for the first user account) that can realistically conflict with the uids of users defined on locally administered networks, potentially leading to account takeover,…
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e.g., by leveraging newuidmap for access to an NFS home directory (or same-host resources in the case of remote logins by these local network users). NOTE: it may also be argued that system administrators should not have assigned uids, within local networks, that are within the range that can occur in /etc/subuid.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Requires documented secure initialization practices and avoidance of insecure defaults in configuration baselines.
Reviewing and updating baseline when components are installed or upgraded prevents initialization with insecure defaults.
Requiring explicit configuration to minimal functionality overrides insecure defaults that would otherwise enable excess capabilities.
Tailoring replaces or augments insecure default initializations with system-specific values and compensating controls before deployment.
Central configuration overrides or replaces insecure default initializations that would otherwise be left unchanged on each system.
SCRM practices during acquisition and configuration management address insecure default initializations shipped by vendors.
Scans detect resources initialized with insecure defaults that create exploitable conditions.
Instruction on secure initialization of security controls prevents leaving resources with insecure defaults after installation.