CVE-2025-46802
Description
A flaw was found in Screen, allowing TTY hijacking during attachment to a multiuser session. The issue with this temporary TTY mode change is that it introduces a race condition that allows any other user in the system to open the caller's TTY for reading and writing for a small period of time.
Statement
This vulnerability is an Important local privilege escalation vector rather than a mere moderate flaw due to its exploitation potential during the short-lived but dangerously permissive window created by chmod(attach_tty, 0666). Even though the exposure of the TTY permissions may appear transient, this window allows attackers with local access to reliably read and inject arbitrary data into the victim’s TTY, including sensitive inputs like passwords or session-specific commands. The race condition inherent in the Attach() function’s logic multiplies the risk since TTY access for the duration of this window can be repeatedly attempted and exploited with high success rates. Furthermore, this vulnerability bypasses the usual privilege separation model of multi-user systems by enabling an unprivileged attacker to subvert the victim’s TTY in ways that can directly compromise the user’s session integrity and lead to further exploitation, such as terminal escape attacks or sophisticated phishing scenarios.
Mitigation
No mitigation is currently available that meets Red Hat Product Security’s standards for usability, deployment, applicability, or stability.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When a race condition makes it possible to bypass a resource cleanup routine or trigger multiple initialization routines, it may lead to resource exhaustion.
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Instability
When a race condition allows multiple control flows to access a resource simultaneously, it might lead the product(s) into unexpected states, possibly resulting in a crash.
Confidentiality,Integrity
Technical Impact: Read Files or Directories; Read Application Data
When a race condition is combined with predictable resource names and loose permissions, it may be possible for an attacker to overwrite or access confidential data (CWE-59).
Access Control
Technical Impact: Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity; Bypass Protection Mechanism
This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.
Frequently Asked Questions
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