Batch Me If You Can: Coverage-guided RPKI Fuzzing at Scale

Computer Science > Cryptography and Security [Submitted on 26 May 2026] Batch Me If You Can: Coverage-guided RPKI Fuzzing at Scale Haya Schulmann, Niklas Vogel The Resource Public Key Infrastructure (RPKI) has become essential to secure inter-domain routing. Despite its critical role, RPKI software remains largely untested beyond shallow parsing. Existing fuzzers, like AFL++ or libFuzzer, do not work well for RPKI as they assume a single, self-contained input per execution, while RPKI repositories contain hundreds of interdependent cryptographically linked objects. Existing fuzzers fail to handle this complexity and lack the ability for precise coverage attribution in multi-object repositories, breaking feedback-based exploration and thereby missing most severe vulnerabilities in RPKI validation. In this paper, we overcome these limitations through novel fuzzing techniques, including continuous sampling and using functions as side-channels for per-object coverage attribution in large input repositories. We further show how parsing inputs to a labeled tree allows structural and semantic mutations while preserving cryptographic validity in mutated repositories. We implement our new techniques into a powerful fuzzing tool called CAT, combining non-sequential fuzzing with our template-agnostic ASN.1 mutation engine to achieve 66x throughput improvement over sequential fuzzing and exploring 24 - 47% more unique code paths compared to libFuzzer and previous work. Evaluating CAT on RPKI validators uncovered 21 previously unknown vulnerabilities with 8 CVEs already assigned (CVSS 7.5 - 9.8). These include a buffer overflow, Denial-of-Service (DoS), and exploitable repository-poisoning logic flaws. We open-source CAT to enable reproducibility, further research, and adaptation of our methods to other complex cryptography-based protocols such as DNSSEC and TLS. Comments: Published at IEEE S&P 2026 Subjects: Cryptography and Security (cs.CR) Cite as: arXiv:2605.26651 [cs.CR]   (or arXiv:2605.26651v1 [cs.CR] for this version)   https://doi.org/10.48550/arXiv.2605.26651 Focus to learn more Submission history From: Niklas Vogel [view email] [v1] Tue, 26 May 2026 07:33:01 UTC (2,663 KB) Access Paper: HTML (experimental) view license Current browse context: cs.CR < prev   |   next > new | recent | 2026-05 Change to browse by: cs 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?)