CVE-2026-1337 in Enterprise Edition
Summary
by MITRE • 02/06/2026
Insufficient escaping of unicode characters in query log in Neo4j Enterprise and Community editions prior to 2026.01 can lead to XSS if the user opens the logs in a tool that treats them as HTML. There is no security impact on Neo4j products, but this advisory is released as a precaution to treat the logs as plain text if using versions prior to 2026.01.
Proof of concept exploit: https://github.com/JoakimBulow/CVE-2026-1337
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Analysis
by VulDB Data Team • 02/26/2026
CVE-2026-1337 represents a cross-site scripting vulnerability in Neo4j database products that stems from inadequate handling of unicode characters within query logs. This vulnerability affects both Neo4j Enterprise and Community editions prior to version 2026.01, where the logging mechanism fails to properly escape unicode sequences that could potentially contain malicious script code. The flaw exists in the query log generation process where user-supplied data containing unicode characters is directly embedded into log files without appropriate sanitization or encoding measures. When these log files are subsequently opened in web-based tools that interpret the content as HTML, the unescaped unicode characters can be executed as malicious scripts, creating a potential XSS attack vector. This vulnerability is classified under CWE-79 as improper neutralization of input during web output, specifically in the context of log file generation and processing. The attack scenario requires an attacker to craft a malicious query containing specially formatted unicode characters that, when logged, will execute malicious JavaScript code in the context of a user's browser when the log file is viewed in a web browser or HTML-aware viewer tool. The vulnerability does not directly impact Neo4j's core security model or database operations, but rather represents a secondary risk that emerges when log files are processed by external tools. According to ATT&CK framework, this maps to T1059.007 for scripting and T1566.001 for spearphishing attachments, as it enables the delivery of malicious code through log file manipulation. The security advisory recommends treating all log files as plain text when using affected versions, which prevents automatic HTML interpretation by web-based tools and eliminates the XSS execution path. Organizations should implement proper log sanitization procedures and ensure that log files are not directly opened in web browsers without proper content filtering. The fix involves upgrading to Neo4j version 2026.01 or later, which includes proper unicode escaping mechanisms in the logging subsystem to prevent malicious code injection through query logs. This vulnerability demonstrates the importance of considering the entire data lifecycle, from database operations through log generation and external processing, when implementing security controls.