We have identified a new heap buffer overflow vulnerability in Samsung’s baseband implementation (mainly used in Exynos chipsets). The vulnerability can be exploited to achieve arbitrary code execution in the baseband runtime. The vulnerability we are disclosing in this advisory affected a wide range of Samsung devices, including phones on the newest Exynos chipsets. The June 2023 issue of the Samsung Mobile Security Bulletin contains this vulnerability as CVE-2023-21517. Vulnerability Details Layer 3 LTE NAS messages are composed of various Information Elements and the Exynos modem implementation defines dedicated parser functions for each IE type. The vulnerability is within the parser function of the Traffic Flow Template IE (3GPP TS 24.