CVE-2026-28271 is a vulnerability in Kiteworks private data network (PDN) products prior to version 9.2.0, caused by improper reliance on reverse DNS resolution for security-critical decisions. Specifically, the product's configuration functionality uses reverse DNS lookups to enforce Server-Side Request Forgery (SSRF) protections. However, this approach is vulnerable to DNS rebinding attacks, where an attacker manipulates DNS responses to bypass these protections. A malicious administrator with privileges can exploit this flaw to circumvent SSRF defenses and gain unauthorized access to internal services that should be inaccessible externally. The vulnerability is classified under CWE-350 (Reliance on Reverse DNS Resolution) and CWE-918 (Server-Side Request Forgery). The CVSS v3.1 base score is 6.5 (medium severity), reflecting that the attack vector is network-based, requires low attack complexity, and privileges of an administrator, but no user interaction. The impact is high on integrity as attackers can access and potentially manipulate internal services. Kiteworks addressed this vulnerability in version 9.2.0 by removing or securing the reverse DNS reliance in the configuration functionality. No known exploits have been reported in the wild as of the publication date.

The vulnerability allows malicious administrators to bypass SSRF protections and access internal services that should be restricted, potentially leading to unauthorized data access, manipulation, or disruption of internal systems. This can compromise the integrity of internal services and may facilitate lateral movement within an organization's network. Since the exploit requires administrator privileges, the risk is elevated primarily when insider threats or compromised administrator accounts exist. Organizations relying on Kiteworks PDN for secure data transfer and internal service isolation could face significant security breaches if this vulnerability is exploited. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially in environments with privileged users who may be malicious or compromised.

1. Upgrade Kiteworks PDN to version 9.2.0 or later immediately to apply the official patch that addresses this vulnerability. 2. Restrict and monitor administrator privileges rigorously to reduce the risk of insider threats exploiting this vulnerability. 3. Implement network segmentation and strict access controls to limit the exposure of internal services even if SSRF protections are bypassed. 4. Employ DNS security measures such as DNSSEC and monitoring for suspicious DNS rebinding activity to detect and prevent exploitation attempts. 5. Conduct regular audits and monitoring of administrative actions within Kiteworks to detect anomalous behavior indicative of exploitation attempts. 6. Consider additional application-layer protections against SSRF, such as validating and sanitizing all outbound requests, independent of DNS resolution. 7. Maintain up-to-date threat intelligence to respond quickly if exploits emerge in the wild.