CVE-2026-118276 in a2ui
Summary
by MITRE • 10/28/2026
A vulnerability was determined in a2ui-project a2ui up to 0.10.6. This vulnerability affects the function formatString of the file renderers/web_core/src/v0_9/basic_catalog/expressions/expression_parser.ts of the component Parser. This manipulation causes resource consumption. The attack may be initiated remotely. The exploit has been publicly disclosed and may be utilized. Patch name: 1f71d1aac1b145ef57c7526f9e0cff316f5934e2. Applying a patch is the recommended action to fix this issue.
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Analysis
by VulDB Data Team • 10/28/2026
The vulnerability identified in the a2ui-project, specifically within versions up to 0.10.6, represents a significant risk related to resource consumption stemming from improper handling of input data within the expression parsing logic. The flaw resides in the formatString function located in the file renderers/web_core/src/v0_9/basic_catalog/expressions/expression_parser.ts. This component is responsible for processing and rendering dynamic content based on user-provided or system-generated expressions. When an attacker supplies a specially crafted input string to this parser, it triggers inefficient computational behavior that leads to excessive consumption of server resources such as CPU cycles or memory allocation. This type of flaw is characteristic of algorithmic complexity vulnerabilities where the execution time grows disproportionately with the size or structure of the input data rather than scaling linearly.
From a technical perspective, this issue aligns closely with CWE-400, which describes Uncontrolled Resource Consumption. In many modern web frameworks and template engines, expression parsers are designed to evaluate complex logic dynamically. However, if these parsers lack proper safeguards against deeply nested structures or repetitive patterns in the input string, they can enter infinite loops or perform redundant calculations that exhaust system resources. The specific function formatString appears to be susceptible to such behavior when processing malformed or maliciously constructed strings. This allows an attacker to trigger a Denial of Service condition without necessarily needing to exploit a code execution flaw. The impact is primarily operational stability rather than data confidentiality or integrity, as the primary consequence is the degradation or complete unavailability of the service due to resource exhaustion.
The attack vector for this vulnerability is remote, meaning that it can be exploited over a network connection such as the internet without requiring prior authentication in many deployment scenarios where user input flows directly into expression parsers. The fact that an exploit has been publicly disclosed indicates that proof-of-concept code or detailed methodologies are available to threat actors. This significantly lowers the barrier for entry, allowing less sophisticated attackers to launch resource exhaustion attacks against systems running affected versions of a2ui. Such attacks can be automated and scaled across multiple targets, potentially leading to widespread service outages if not mitigated promptly. The public disclosure also implies that security monitoring tools may already have signatures or heuristics capable of detecting attempts to exploit this specific flaw in network traffic logs.
To mitigate this vulnerability, the immediate recommendation is to apply the patch identified by commit hash 1f71d1aac1b145ef57c7526f9e0cff316f5934e2. This update likely introduces input validation limits, recursion depth restrictions, or optimized parsing algorithms that prevent the excessive resource consumption associated with malformed inputs. Organizations should prioritize updating their a2ui dependencies to version 0.10.7 or later where this fix is included. In addition to patching, it is advisable to implement web application firewalls rules that detect and block suspicious patterns in expression strings before they reach the parser. Monitoring server metrics for unusual spikes in CPU usage correlated with specific endpoint requests can also help identify ongoing exploitation attempts. Regular security assessments and code reviews focusing on input validation in template engines are essential preventive measures against similar algorithmic complexity vulnerabilities in future development cycles.