CVE-2024-29510
Description
A flaw in Ghostscript has been identified where the uniprint device allows users to pass various string fragments as device options. These strings, particularly upWriteComponentCommands and upYMoveCommand, are treated as format strings for gp_fprintf and gs_snprintf. This lack of restriction permits arbitrary format strings with multiple specifiers, potentially leading to data leakage from the stack and memory corruption. In RHEL 9 or newer, an attacker could exploit this vulnerability to temporarily disable Ghostscript’s SAFER mode, which prevents Postscript code from executing commands or opening arbitrary files during the current invocation.
Mitigation
Passing the -dSAFER safety argument on the command line prevents the issue by locking security-related variables after Ghostscript's initialization. In RHEL 9, -dSAFER is enabled by default, ensuring that insecure commands are rejected in a safer environment. The versions of Ghostscript in RHEL 7 and RHEL 8 have an older implementation of SAFER mode that is not enabled by default, but can be enabled by passing -dSAFER on the command line when invoking Ghostscript. This older SAFER mode implementation denies Postscript code the ability to change the output device, and therefore prevents malicious Postscript code from selecting the uniprint output device in order to exploit the format string vulnerabilities in its upWriteComponentCommands and upYMoveCommand parameters. On RHEL 7 and RHEL 8, we recommend always passing -dSAFER on the command line, and avoiding manually selecting the uniprint output device on the command line.
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 | 5.5 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | Required | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | None | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
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