Description

IBM i 7.6, 7.5, 7.4, and 7.3 could allow a local attacker to gain elevated privileges due to improper validation of the LANG environment variable.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-08-13T20:17:17.530Z",
  "pubdate": "2026-08-13T20:17:17.530Z",
  "executiveSummary": "A local privilege escalation vulnerability exists in IBM i versions 7.6, 7.5, 7.4, and 7.3.\nThe vulnerability arises due to improper validation of the LANG environment variable within the affected systems.\nA locally authenticated attacker can exploit this flaw to execute arbitrary operations or manipulate execution contexts, ultimately leading to the acquisition of elevated system privileges.\nThe primary risk implication involves unauthorized access escalation from a standard user context to a higher privileged execution state, potentially compromising the integrity and confidentiality of the entire operating system environment.\nExploitation requires local access to the target system and relies on manipulating environment variables during program execution.\nNo specific remote exploitation vectors or specialized authentication bypasses are mandated beyond initial local execution capabilities.",
  "technicalDetails": "The root cause of the vulnerability stems from insufficient input sanitization and improper validation logic applied to the LANG environment variable by vulnerable system components within IBM i.\nEnvironment variables such as LANG dictate localization and language settings, which are frequently processed by underlying system binaries, shell scripts, or compiled binaries during startup or routine execution flows.\nWhen a local attacker provisions a maliciously crafted or malformed string into the LANG environment variable prior to invoking a vulnerable setuid, setgid, or privileged binary, the inadequate validation routines fail to properly restrict the input length, syntax, or expected character sets.\nThis failure in input verification can lead to memory corruption conditions, unintended execution path redirection, or the improper parsing of runtime configurations within the privileged context.\nThe affected component involves operating system utilities and binary execution handlers responsible for localization parsing across IBM i versions 7.6, 7.5, 7.4, and 7.3.\nThe attack flow proceeds as follows: First, the local attacker establishes an authenticated session on the target IBM i instance using standard, unprivileged credentials. Second, the attacker deliberately modifies the local shell environment by exporting a specially crafted payload or unexpected input sequence via the LANG environment variable. Third, the attacker executes a vulnerable system program or privileged utility that relies on processing this environment variable without rigorous bounds checking or sanitization. Fourth, upon processing the corrupted or unexpected localization parameter, the application encounters an error condition or logic flaw that can be leveraged to hijack execution flow. Finally, the attacker achieves code execution within the security context of the targeted privileged process, resulting in successful local privilege escalation and full system compromise capabilities."
}