CVE-2022-26650 in ShenYu
Summary
by MITRE • 05/17/2022
In Apache ShenYui, ShenYu-Bootstrap, RegexPredicateJudge.java uses Pattern.matches(conditionData.getParamValue(), realData) to make judgments, where both parameters are controllable by the user. This can cause an attacker pass in malicious regular expressions and characters causing a resource exhaustion. This issue affects Apache ShenYu (incubating) 2.4.0, 2.4.1 and 2.4.2 and is fixed in 2.4.3.
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Analysis
by VulDB Data Team • 05/24/2022
The vulnerability identified as CVE-2022-26650 resides within Apache ShenYu's ShenYu-Bootstrap component, specifically in the RegexPredicateJudge.java file where regular expression pattern matching is performed. This flaw represents a classic example of a regular expression denial of service (ReDoS) vulnerability that allows attackers to exploit resource exhaustion through crafted malicious inputs. The vulnerability occurs when the system processes user-controllable data through the Pattern.matches() method, which accepts both the conditionData.getParamValue() and realData parameters directly from user input without proper sanitization or validation. This design creates a dangerous scenario where an attacker can construct specially crafted regular expressions that cause the matching engine to consume excessive computational resources.
The technical implementation of this vulnerability stems from the way Java's Pattern.matches() method handles regular expression evaluation. When an attacker supplies malicious regular expressions containing certain patterns such as nested quantifiers or backtracking constructs, the regular expression engine enters into exponential time complexity behavior, leading to significant CPU resource consumption and potential system hangs or crashes. The vulnerability is particularly dangerous because both parameters in the matching operation are fully controllable by the attacker, eliminating the need for complex exploitation techniques. This weakness directly maps to CWE-400, which classifies issues related to excessive resource consumption, and specifically aligns with CWE-1321, which addresses regular expression denial of service vulnerabilities.
The operational impact of this vulnerability extends beyond simple resource exhaustion, potentially compromising the availability and stability of the entire Apache ShenYu gateway system. Attackers can leverage this vulnerability to perform denial of service attacks against the application, causing legitimate requests to fail or the system to become unresponsive. In a production environment, this could result in significant service disruption and potential financial losses. The vulnerability affects multiple versions of Apache ShenYu including 2.4.0, 2.4.1, and 2.4.2, making it a widespread concern for organizations that have not yet upgraded to the patched version 2.4.3. From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a critical threat vector that can be exploited without requiring elevated privileges or specialized knowledge.
Organizations should implement immediate mitigations including upgrading to Apache ShenYu version 2.4.3, which contains the necessary patches to address this vulnerability. Additionally, implementing input validation and sanitization measures can help reduce the attack surface by filtering potentially malicious regular expressions before they reach the matching engine. Security teams should also consider implementing rate limiting and monitoring for unusual resource consumption patterns that might indicate exploitation attempts. The fix in version 2.4.3 likely involves proper validation of regular expression inputs and potentially implementing timeouts or resource limits for pattern matching operations to prevent the exponential time complexity behavior that leads to resource exhaustion.