CVE-2026-76729 in Instant ON
Summary
by MITRE • 09/29/2026
A format string vulnerability in the API endpoint of HPE Networking Instant ON APs could allow an authenticated remote attacker with high privileges to cause memory corruption with a modified input. Successful exploitation could allow an attacker to provoke a denial-of-service condition or remote code execution in the affected system function.
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Analysis
by VulDB Data Team • 09/29/2026
The identified vulnerability represents a critical security flaw within the application programming interface of HPE Networking Instant ON access points, specifically classified as a format string vulnerability. This type of defect arises when user-supplied input is incorrectly passed to functions that interpret it as a format specification rather than literal data. In this context, an authenticated remote attacker possessing high-level privileges can manipulate specific API endpoints by injecting specially crafted strings containing format specifiers such as percent signs followed by conversion characters like s or x. The underlying software fails to properly validate or sanitize these inputs before processing them through vulnerable formatting routines, leading to unintended memory operations that compromise the integrity of the system's execution environment.
The technical mechanism behind this flaw involves the improper handling of variable arguments in C-style string formatting functions. When an attacker provides a modified input containing format specifiers, the application interprets these as instructions to read from or write to arbitrary locations on the stack or heap. This misinterpretation allows for both information disclosure and memory corruption. The immediate operational impact includes severe instability within the affected system function, which can be exploited to trigger a denial-of-service condition by crashing the service process or exhausting available resources through infinite loops caused by malformed pointers. More critically, if the attacker can control the data written during this exploitation phase, they may achieve remote code execution with the privileges of the compromised application, effectively gaining full administrative control over the network infrastructure device.
From a classification perspective, this vulnerability aligns with Common Weakness Enumeration identifier CWE-134, which covers use of externally-controlled format string. This weakness is particularly dangerous because it bypasses standard input validation checks that might otherwise prevent buffer overflow attacks by focusing on how data is interpreted rather than just its size. Furthermore, the exploitation technique maps to MITRE ATT&CK techniques related to command and script interpretation as well as potential privilege escalation pathways, allowing an adversary who has already gained high-level access to further entrench their presence or escalate privileges if additional layers of authentication are present in adjacent systems. The ability to execute arbitrary code remotely makes this a severe threat vector for network infrastructure devices that often serve as gateways between internal networks and external connections.
Mitigation strategies must prioritize immediate patching by the vendor, as format string vulnerabilities typically require source-level fixes to ensure proper input sanitization before passing data to formatting functions. Administrators should enforce strict access controls on API endpoints, ensuring that only necessary services are exposed and that authentication mechanisms are robustly implemented to prevent unauthorized high-privilege access even if other security boundaries are breached. Network segmentation can also limit the blast radius of such an exploit by isolating management interfaces from general user traffic. Additionally, implementing runtime application self-protection or intrusion detection systems capable of detecting anomalous memory access patterns may provide a layer of defense against exploitation attempts while patches are being deployed across the infrastructure.