A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.
Impact:
This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Credits
F5 acknowledges Ming Xuan, DKD (@pidifn), Ji'an Zhou, and Zhen Yan of AntAISecurityLab, Rafael Gacek, Sergii Negodiuk of EVO.company, Lam Jun Rong of Calif.io, Mufeed VH of Winfunc Research (winfunc.com), Vexera AI (https://vexera.ai), Tu Tran Dinh (@1w4y), Stan Shaw (cyberstan), qianshuidewajueji, zenneth (randomguy6407), Zhenpeng (Leo) Lin of depthfirst, Lukas Johannes Moeller, Melih Tolga Sahin of Vodafone Türkiye, Ayoub Nabil Boubagrat (GitHub: @ayoubnabil), and Milan Jovic (Kljunowsky) for independently bringing this issue to our attention and following the highest standards of coordinated disclosure.
