Description

A pre-authentication heap-based buffer overflow vulnerability has been identified in the SonicOS SSL-VPN service, which could potentially enable a remote unauthenticated attacker to cause an application level denial of service.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-11-06T19:17:57.567Z",
  "pubdate": "2026-11-06T19:17:57.567Z",
  "executiveSummary": "A pre-authentication heap-based buffer overflow vulnerability exists within the SonicOS SSL-VPN service component.\nThis security flaw allows a remote, unauthenticated attacker to inject malicious data into the heap memory of the application process.\nThe primary impact of this vulnerability is an application-level denial of service (DoS), which can lead to service interruption or instability of the SSL-VPN gateway.\nBecause the vulnerability is reachable without authentication, it exposes the appliance to potential disruption from any network-adjacent attacker capable of reaching the SSL-VPN endpoint.\nThe risk is categorized as high for organizations relying on SSL-VPN for secure remote access, as exploitation requires no valid user credentials or prior system access.\nSuccessful exploitation forces an abnormal termination of the affected service, necessitating administrative intervention to restore normal operations.",
  "technicalDetails": "The vulnerability originates from improper memory management during the processing of incoming requests by the SonicOS SSL-VPN service, specifically within the handling of pre-authentication handshake or initialization packets.\nThe root cause is a heap-based buffer overflow, where input data exceeds the bounds of an allocated memory buffer on the process heap. This occurs when the service fails to sufficiently validate the length of user-supplied data before copying it into a fixed-size heap buffer.\nThe attack flow begins when a remote, unauthenticated attacker initiates a connection to the SSL-VPN service. The attacker sends a crafted network packet containing a payload designed to trigger the overflow condition during the initial parsing phase of the communication protocol.\nUpon reaching the vulnerable function, the application attempts to copy the excessive data into the heap buffer without adequate bounds checking. This action overwrites adjacent memory structures within the heap, potentially corrupting application control data or heap management metadata.\nThe corruption of heap metadata or critical internal objects leads to an invalid memory access or a failed sanity check within the memory allocator, causing the SSL-VPN process to crash. This effectively results in a denial of service, rendering the VPN functionality unavailable to legitimate users.\nAs the vulnerability resides in the pre-authentication stack, the attack requires no valid credentials. The attack surface is exposed directly through the SSL-VPN interface, typically accessible over the public internet, increasing the likelihood of automated exploitation attempts.\nWhile the primary impact identified is a denial of service, heap-based buffer overflows often involve memory corruption that, under specific environmental conditions, could theoretically be leveraged for arbitrary code execution if the memory layout and pointer references can be predictably influenced by the attacker. However, the current scope focuses on the application-level instability caused by the overflow."
}