CVE-2026-53671
PREVAIL: Context-write no-op in do_mem_store allows unsafe eBPF programs to pass verification
- State
- Published
- Severity
- 9.3 Critical
- Published
- Sep 2, 2026
- Updated
- Sep 5, 2026
- Reserved
- Jun 9, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.3 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N | GitHub_M |
Weaknesses
- CWE-682 Incorrect Calculation
Affected Products
| Product | Versions |
|---|---|
prevailvbpf |
|
References
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