CVE-2026-88839
Description
BusyBox passwd/group tokenize() references a stale endpoint pointer after trimming, causing an out-of-bounds write of heap pointers.
Statement
On Fedora 44, /etc/group is owned by root:root with mode 0644 and protected by SELinux. Only root can modify this file. Since root privileges are required to inject the malformed entry, the vulnerability adds no practical value on Fedora, as an attacker with root access already has full system control.
Mitigation
Ensure /etc/group and /etc/passwd are writable only by root and protected by mandatory access controls. Monitor these files for unauthorized modifications. Upstream should fix tokenize() to recompute tokenize_end after trimming.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.7 | N/A | 6.7 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | High | N/A | High |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Acknowledgements
Red Hat would like to thank Shubham Raj (Causal Security) for reporting this issue.
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