Street-Legal Physical-World Adversarial Rim for License Plates

Computer Science > Computer Vision and Pattern Recognition [Submitted on 2 Apr 2026] Street-Legal Physical-World Adversarial Rim for License Plates Nikhil Kalidasu, Sahana Ganapathy Automatic license plate reader (ALPR) systems are widely deployed to identify and track vehicles. While prior work has demonstrated vulnerabilities in ALPR systems, far less attention has been paid to their legality and physical-world practicality. We investigate whether low-resourced threat actors can engineer a successful adversarial attack against a modern open-source ALPR system. We introduce the Street-legal Physical Adversarial Rim (SPAR), a physically realizable white-box attack against the popular ALPR system fast-alpr. SPAR requires no access to ALPR infrastructure during attack deployment and does not alter or obscure the attacker's license plate. Based on prior legislation and case law, we argue that SPAR is street-legal in the state of Texas. Under optimal conditions, SPAR reduces ALPR accuracy by 60% and achieves an 18% targeted impersonation rate. SPAR can be produced for under $100, and it was implemented entirely by commercial agentic coding assistants. These results highlight practical vulnerabilities in modern ALPR systems under realistic physical-world conditions and suggest new directions for both attack and defense. Comments: 20 pages, 8 figures, 5 tables, submitted to Security in Machine Learning Applications 2026 Subjects: Computer Vision and Pattern Recognition (cs.CV); Cryptography and Security (cs.CR) ACM classes: I.2.10; I.4.m Cite as: arXiv:2604.02457 [cs.CV]   (or arXiv:2604.02457v1 [cs.CV] for this version)   https://doi.org/10.48550/arXiv.2604.02457 Focus to learn more Submission history From: Nikhil Kalidasu [view email] [v1] Thu, 2 Apr 2026 18:41:29 UTC (19,902 KB) Access Paper: HTML (experimental) view license Current browse context: cs.CV < prev   |   next > new | recent | 2026-04 Change to browse by: cs cs.CR References & Citations NASA ADS Google Scholar Semantic Scholar Export BibTeX Citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer (What is the Explorer?) Connected Papers Toggle Connected Papers (What is Connected Papers?) Litmaps Toggle Litmaps (What is Litmaps?) scite.ai Toggle scite Smart Citations (What are Smart Citations?) Code, Data, Media Demos Related Papers About arXivLabs Which authors of this paper are endorsers? | Disable MathJax (What is MathJax?)