CVE-2026-53878 in Django
Summary
by MITRE • 07/07/2026
An issue was discovered in Django 6.0 before 6.0.7 and 5.2 before 5.2.16. `DomainNameValidator` does not prohibit newlines in domain names (unless used via a form field, since `CharField` strips newlines). If an application uses values with newlines in an HTTP response, header injection can occur. Django itself is unaffected because `HttpResponse` prohibits newlines in HTTP headers. Earlier, unsupported Django series (such as 5.0.x, 4.1.x, and 3.2.x) were not evaluated and may also be affected. Django would like to thank Bence Nagy for reporting this issue.
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Analysis
by VulDB Data Team • 07/07/2026
The vulnerability resides in Django's DomainNameValidator implementation across versions 6.0 before 6.0.7 and 5.2 before 5.2.16, where the validator fails to properly sanitize domain names containing newline characters. This flaw represents a classic input validation weakness that can be categorized under CWE-172 as improper handling of input containing control characters. The issue specifically affects applications that process domain name inputs without proper sanitization, creating potential attack vectors for header injection attacks.
The technical mechanism behind this vulnerability involves the DomainNameValidator's insufficient filtering of control characters including newline sequences within domain name strings. While Django's CharField automatically strips newlines during form field processing, applications that directly utilize the DomainNameValidator without such preprocessing remain susceptible to malicious input manipulation. When these malformed domain names are subsequently processed in HTTP response contexts, they can introduce newline characters into HTTP headers, enabling header injection attacks.
The operational impact of this vulnerability extends beyond simple validation failures and can enable attackers to manipulate HTTP responses through carefully crafted domain name inputs. This represents a significant security risk as it allows for potential header manipulation that could be exploited to inject malicious headers, redirect traffic, or perform other unauthorized actions within the web application's response handling. The vulnerability affects applications that process user-supplied domain names in contexts where HTTP headers are constructed, making it particularly dangerous in environments where such inputs are not properly sanitized.
Organizations using affected Django versions should immediately upgrade to the patched releases 6.0.7 and 5.2.16 to mitigate this risk. Additionally, defensive programming practices should be implemented including explicit input sanitization for domain names before processing, validation of all user-supplied inputs containing potentially dangerous characters, and regular security auditing of input handling code paths. The issue demonstrates the importance of comprehensive input validation across all application layers rather than relying solely on framework-level protections, as highlighted by ATT&CK technique T1071.004 for application layer protocol manipulation.
Security teams should also consider implementing network-based monitoring to detect unusual header injection patterns and establish proper logging of domain name processing activities. The vulnerability underscores the need for consistent security practices across all software components and the importance of thorough testing of input validation logic. Given that earlier unsupported Django versions may also be affected, organizations should conduct comprehensive audits of their Django installations to ensure all components are properly updated and secured against this class of attack vector.