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high·Product Based Web Vulnerabilities·Updated Nov 8, 2025

CVE-2018-19518 Scanner

CVE-2018-19518 Scanner - Remote Code Execution (RCE) vulnerability in PHP imap

Est. Time~10 seconds
Scan TypeSingle Scan
Targetsurl
CostFree
3.5k
Times Used
continuous scan runs
4.2k
Continuously Checked
assets under CS
0
Vulnerabilities Found
confirmed findings
References
CVECVE-2018-19518
7.5
CVSS

University of Washington IMAP Toolkit 2007f on UNIX, as used in imap_open() in PHP and other products, launches an rsh command (by means of the imap_rimap function in c-client/imap4r1.c and the tcp_aopen function in osdep/unix/tcp_unix.c) without preventing argument injection, which might allow remote attackers to execute arbitrary OS commands if the IMAP server name is untrusted input (e.g., entered by a user of a web application) and if rsh has been replaced by a program with different argument semantics. For example, if rsh is a link to ssh (as seen on Debian and Ubuntu systems), then the attack can use an IMAP server name containing a "-oProxyCommand" argument.

Attack Vector
-
Privileges Req.
-
User Interaction
-
Affected
n/aby n/a
n/a
Updated Aug 21, 2026View on NVD →
Detail

PHP imap is a versatile toolkit utilized predominantly in UNIX systems for handling IMAP connections. It is implemented in various web applications to facilitate email retrieval and processing. Developers employ this kit to streamline connections to email servers, optimizing communication through IMAP functionalities. Its integration in PHP expands its utility, allowing it to be embedded in web applications for email manipulation. The software is robust and widely distributed, enjoying significant use in systems requiring email management. Its adoption spans both personal projects and enterprise-level applications due to its comprehensive feature set and ease of integration.

The vulnerability lies in the University of Washington IMAP Toolkit's handling of command inputs within its imap_open() in PHP. It allows remote command execution through inadequate argument handling when interfacing with the system's rsh or its replacements. This flaw can be exploited if the IMAP server name contains malicious input, leading to potential arbitrary OS command execution. Attackers could leverage this behavior particularly where rsh is replaced by ssh, enabling severe exploitation scenarios. The vulnerability is surreptitiously dangerous if these commands are not scrutinized properly, posing a significant risk. Its exploitability gains prominence in environments where input validation is lax, potentially compromising system integrity.

The vulnerability technically arises from improper handling of server names processed via the imap_rimap function. The tcp_aopen function, when executed, lacks safeguards against argument injection, leading to vulnerabilities. Exploitation involves tailoring inputs that manipulate expected argument sequences, enabling unintended OS command execution. The flaw is identified in scenarios where parameters are not correctly sanitized, leading to bypassing of input constraints. This vulnerability is notable in systems misconfigured to handle command manipulations naively. In particular, the PHP imap toolkit's insecurities manifest under these conditions, exhibiting a clear pathway to execution vulnerabilities.

If exploited, this vulnerability could have far-reaching implications for affected systems. It could grant attackers unauthorized access to perform arbitrary command execution, leading to potential data breaches and loss of data integrity. Additionally, systems could encounter service disruption or be leveraged in broader attack strategies, compromising network security. The attack vector could extend to enabling backdoors, data exfiltration, and unauthorized control over system operations. Organizations using this setup could face significant security risks, heightened further in networked environments. As such, addressing this vulnerability is crucial to maintaining operational security and data confidentiality.

REFERENCES

Solution Advice
  • Apply patches or updates provided by the software vendor to the latest version.
  • Implement input validation techniques to sanitize untrusted inputs to the server name parameter.
  • Restrict or disable the use of the rsh command unless explicitly necessary for operations.
  • Ensure that IMAP server name inputs are sourced from trusted origins and validated rigorously.
  • Investigate hardening the security configurations of PHP and associated IMAP integrations.
  • Regularly review and audit security settings to identify potentially exploitable conditions.

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CVE-2018-19518 Scanner - Remote Code Execution (RCE) vulnerability in PHP imap | S4E