CVE-2026-101955: CWE-121 Stack-based Buffer Overflow in Juniper Networks Junos OS

This vulnerability (CWE-121) exists in the UTM Anti-Spam SBL feature of Juniper Networks Junos OS on SRX series devices. An attacker can exploit a stack-based buffer overflow by injecting a malformed DNS packet, potentially leading to arbitrary code execution or denial of service. The vulnerability affects multiple versions of Junos OS prior to specific patch releases as detailed in the affected versions list. The CVSS 3.1 score is 8.1, indicating high severity with network attack vector, high complexity, no privileges required, no user interaction, and impacts confidentiality, integrity, and availability.

Successful exploitation can lead to arbitrary code execution or denial of service on affected Junos OS SRX devices with Anti-Spam SBL inspection enabled. This compromises the confidentiality, integrity, and availability of the affected system. The attacker does not require authentication to exploit this vulnerability.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official patch or workaround information is provided in the available data. Users should monitor Juniper Networks advisories for updates and apply patches once available. Until then, consider disabling Anti-Spam SBL inspection if feasible to reduce exposure.