🚨 CVE-2026-53671
PREVAIL is a Polynomial-Runtime EBPF Verifier using an Abstract Interpretation Layer. Prior to version 0.2.4, the abstract transformer in prevail treats writes through a T_CTX-typed base register as a silent no-op: do_mem_store in src/crab/ebpf_transformer.cpp only models T_STACK stores, and the checker's T_CTX bounds arm never tests AccessType::write. An attacker can craft an eBPF program that overwrites a context field (e.g., ctx->data), reload that field typed as T_PACKET, and dereference an attacker-controlled address — and prevail will report the program as safe. This issue has been patched in version 0.2.4.
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GitHub
Reject writes to read-only context pointer fields · vbpf/prevail@de65234
A write through a `T_CTX`-typed base register was accepted while the abstract
transformer modeled it as a silent no-op (`do_mem_store` handles only `T_STACK`
stores) and the checker's `T_CT...
September 2, 2026 18
