CVE-2016-1000022 in negotiator
Summary
by MITRE
negotiator before 0.6.1 is vulnerable to a regular expression DoS
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Analysis
by VulDB Data Team • 03/16/2024
The vulnerability identified as CVE-2016-1000022 affects the negotiator library version 0.6.1 and earlier, representing a significant security concern related to regular expression denial of service attacks. This flaw exists within the HTTP content negotiation functionality that processes Accept headers in web applications, making it a critical issue for any system relying on proper content type handling. The vulnerability stems from the library's insufficient validation of user-supplied input when processing HTTP Accept headers, which can be exploited to cause excessive CPU consumption through carefully crafted malicious input patterns.
The technical implementation of this vulnerability involves the negotiator library's use of regular expressions to parse and match content type specifications in HTTP requests. When an attacker crafts a malicious Accept header containing specially designed regular expression patterns, the library's regex engine becomes susceptible to catastrophic backtracking behavior. This occurs because the regular expressions used for parsing content negotiation headers contain constructs that cause exponential time complexity during pattern matching, allowing an attacker to consume excessive computational resources. The vulnerability manifests as a denial of service condition where legitimate requests cannot be processed due to the system being overwhelmed by the resource-intensive regex operations.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by attackers to perform resource exhaustion attacks against web applications using the negotiator library. Systems affected by this vulnerability may experience complete service unavailability, increased latency, and potential system crashes when processing malicious requests. The attack can be executed with minimal resources and requires no authentication, making it particularly dangerous in production environments where the library is widely deployed. This vulnerability directly maps to CWE-400, which categorizes the issue as an Uncontrolled Resource Consumption vulnerability, and aligns with ATT&CK technique T1499.004 for Network Denial of Service attacks. Organizations using vulnerable versions of negotiator may face extended downtime, degraded performance, and potential financial losses due to service unavailability.
Mitigation strategies for this vulnerability include immediate upgrading to negotiator version 0.6.1 or later, which contains the necessary patches to address the regular expression parsing issues. Security teams should also implement input validation and sanitization measures at the application level to filter out potentially malicious Accept headers before they reach the negotiator library. Additionally, rate limiting and request monitoring can help detect and prevent exploitation attempts by identifying unusual patterns of resource consumption. Organizations should conduct thorough testing of the updated library in their environments to ensure compatibility and verify that the patch effectively resolves the vulnerability without introducing regressions. Network-level protections such as web application firewalls can provide additional defense-in-depth measures to detect and block malicious requests targeting this specific vulnerability.