The product uses the chroot() system call to create a jail, but does not change the working directory afterward. This does not prevent access to files outside of the jail.
Improper use of chroot() may allow attackers to escape from the chroot jail. The chroot() function call does not change the process's current working directory, so relative paths may still refer to file system resources outside of the chroot jail after chroot() has been called.

Resultant

The chroot() system call allows a process to change its perception of the root directory of the file system. After properly invoking chroot(), a process cannot access any files outside the directory tree defined by the new root directory. Such an environment is called a chroot jail and is commonly used to prevent the possibility that a processes could be subverted and used to access unauthorized files. For instance, many FTP servers run in chroot jails to prevent an attacker who discovers a new vulnerability in the server from being able to download the password file or other sensitive files on the system.

Implementation
REALIZATION: This weakness is caused during implementation of an architectural security tactic.

High

Confidentiality
Read Files or Directories

Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
High

Consider the following source code from a (hypothetical) FTP server:

chroot("/var/ftproot");...fgets(filename, sizeof(filename), network);localfile = fopen(filename, "r");while ((len = fread(buf, 1, sizeof(buf), localfile)) != EOF) {fwrite(buf, 1, sizeof(buf), network);}fclose(localfile);

This code is responsible for reading a filename from the network, opening the corresponding file on the local machine, and sending the contents over the network. This code could be used to implement the FTP GET command. The FTP server calls chroot() in its initialization routines in an attempt to prevent access to files outside of /var/ftproot. But because the server does not change the current working directory by calling chdir("/"), an attacker could request the file "../../../../../etc/passwd" and obtain a copy of the system password file.

File or Directory

Directory Restriction

SFP17
Failed chroot jail

Allowed
This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

7 Pernicious Kingdoms
2006-07-19
Draft 3
2006-07-19

CWE Content Team
MITRE
2008-09-08
updated Applicable_Platforms, Background_Details, Description, Relationships, Taxonomy_Mappings, Weakness_Ordinalities

CWE Content Team
MITRE
2008-10-14
updated Description

CWE Content Team
MITRE
2009-03-10
updated Demonstrative_Examples

CWE Content Team
MITRE
2009-05-27
updated Demonstrative_Examples

CWE Content Team
MITRE
2010-12-13
updated Demonstrative_Examples, Name

CWE Content Team
MITRE
2011-06-01
updated Common_Consequences

CWE Content Team
MITRE
2012-05-11
updated Relationships

CWE Content Team
MITRE
2014-07-30
updated Relationships, Taxonomy_Mappings

CWE Content Team
MITRE
2017-11-08
updated Affected_Resources, Causal_Nature, Modes_of_Introduction, Relationships

CWE Content Team
MITRE
2020-02-24
updated References

CWE Content Team
MITRE
2023-01-31
updated Description

CWE Content Team
MITRE
2023-04-27
updated Detection_Factors, Relationships

CWE Content Team
MITRE
2023-06-29
updated Mapping_Notes

Directory Restriction
Failure to Change Working Directory in chroot Jail