CVE-2003-0593 in Web Browser
Summary
by MITRE
Opera allows remote attackers to bypass intended cookie access restrictions on a web application via "%2e%2e" (encoded dot dot) directory traversal sequences in a URL, which causes Opera to send the cookie outside the specified URL subsets, e.g. to a vulnerable application that runs on the same server as the target application.
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Analysis
by VulDB Data Team • 07/15/2019
This vulnerability in Opera browsers represents a critical directory traversal flaw that undermines web application security through improper cookie handling mechanisms. The issue manifests when users navigate to URLs containing encoded directory traversal sequences such as "%2e%2e" which represents the ".." characters in URL encoding. When Opera processes these malformed URLs, it fails to properly enforce cookie access restrictions that should limit cookie transmission to specific URL subsets. This technical deficiency allows cookies intended for restricted paths to be transmitted to unintended destinations, effectively bypassing the web application's security boundaries.
The operational impact of this vulnerability extends beyond simple cookie leakage to create significant attack vectors for remote adversaries. When a victim visits a maliciously crafted URL containing the directory traversal sequence, Opera's browser behavior causes it to send cookies that should remain restricted to the target application's specific path to any web application running on the same server. This creates a cross-application cookie leakage scenario where sensitive authentication tokens, session identifiers, or other confidential cookie data can be accessed by malicious applications sharing the same server infrastructure. The vulnerability essentially transforms the browser's cookie management from a security boundary into a potential attack surface.
From a cybersecurity perspective, this vulnerability aligns with CWE-22 directory traversal weaknesses and represents a specific implementation flaw in Opera's URL parsing and cookie handling components. The issue demonstrates how browser vendors must carefully implement security controls to prevent path traversal attacks from affecting cookie security policies. The ATT&CK framework categorizes this under credential access techniques where adversaries exploit browser implementation flaws to obtain unauthorized access to web application sessions. The vulnerability's exploitation requires minimal user interaction beyond visiting a malicious webpage, making it particularly dangerous in phishing or drive-by download scenarios.
Security mitigations for this vulnerability require multiple layers of protection including browser updates from Opera to address the specific URL parsing flaw, proper web application configuration to implement robust cookie security attributes such as SameSite, Secure, and HttpOnly flags, and server-side implementation of additional access controls to prevent cross-application cookie leakage. Network administrators should also consider implementing web application firewalls that can detect and block suspicious directory traversal patterns in URLs. The vulnerability underscores the importance of thorough browser security testing and the need for vendors to maintain strict adherence to web security standards to prevent such implementation flaws from creating exploitable conditions for remote attackers.