CVE-2026-81827 in Flowintel
Summary
by MITRE • 08/27/2026
Affected versions of Flowintel incorrectly attempted to validate login email addresses by calling Email(email). That does not perform WTForms field validation; it merely constructs a validator object.
Consequently, malformed attacker-controlled email input could continue through the login process and be written to security-relevant logs. The vulnerable code inserted the supplied email into both a warning log and the custom audit logger. Since CR/LF characters were not escaped, an unauthenticated attacker could potentially inject additional physical log lines or forge misleading log entries.
The patch corrects the validation call to Email()(form, form.email), changes the standard logging call to parameterized logging, and introduces _sanitize_log_fragment() so carriage returns and line feeds are encoded instead of creating new records.
Version impacted >=3.3.0
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Analysis
by VulDB Data Team • 08/27/2026
Flowintel versions starting from 3.3.0 contain a critical input validation flaw within the authentication module that allows unauthenticated attackers to perform log injection attacks. The vulnerability stems from an incorrect implementation of email address validation during the login process. Instead of invoking the full validation method provided by WTForms, which checks for format compliance and other constraints, the application merely instantiated the Email validator object without executing its validate function. This oversight means that malformed or maliciously crafted input is not rejected at the point of entry but proceeds through the authentication workflow as if it were a valid credential identifier.
The operational impact of this flaw is significant because the unvalidated email string is subsequently written to security-relevant logging systems, including both standard warning logs and custom audit loggers. Because the application fails to sanitize special characters such as carriage returns and line feeds before writing these entries, an attacker can inject arbitrary text into the log files. By inserting newline characters within the email field during login attempts, a malicious actor can break out of the intended single-line log entry format. This capability allows for the injection of additional physical log lines that appear to originate from legitimate system events or other users.
This vulnerability aligns with CWE-117, Improper Output Neutralization for Logs, as the application fails to properly neutralize special elements in user input before including them in a log file. Furthermore, it relates to CWE-20, Improper Input Validation, due to the failure to enforce expected data formats on critical authentication fields. From an offensive security perspective, this flaw supports techniques associated with ATT&CK T1564, Log Hidden, where adversaries manipulate logs to conceal their activities or create confusion for incident responders. The ability to forge misleading log entries can obscure real attack patterns and make forensic analysis more difficult by introducing noise and false positives into the audit trail.
The consequences of successful exploitation extend beyond mere data corruption. Attackers may use this technique to evade detection mechanisms that rely on specific string matches within logs, effectively hiding their presence or actions from security monitoring tools. Additionally, if log aggregation systems are compromised through subsequent injection vectors enabled by these malformed entries, the integrity of centralized logging infrastructure could be jeopardized. The lack of proper sanitization also poses a risk for downstream processes that parse log files, potentially leading to application errors or further exploitation depending on how those logs are consumed.
The provided patch addresses this vulnerability through multiple defensive layers. First, it corrects the validation logic by properly invoking the WTForms validator method with the appropriate form context and field data, ensuring that only syntactically valid email addresses proceed past authentication checks. Second, the standard logging call is updated to use parameterized logging, which helps prevent certain types of injection attacks by separating code from data. Most importantly, a new sanitization function named _sanitize_log_fragment() has been introduced specifically for log output. This function encodes carriage returns and line feeds, thereby preventing attackers from breaking out of the current log entry and injecting additional lines or forging entries that mimic legitimate system activity.
To mitigate this risk in environments where immediate patching is not feasible, administrators should implement strict input validation at the network perimeter using Web Application Firewalls configured to reject requests containing newline characters within authentication fields. Additionally, enabling comprehensive monitoring for anomalous patterns in log files, such as unexpected line breaks or unusual character sequences in login-related entries, can help detect exploitation attempts. Regular audits of logging configurations and ensuring that all user-supplied data is sanitized before being written to any persistent storage are essential practices for maintaining the integrity of security logs and preventing similar vulnerabilities from impacting organizational defenses.