by Kastro
Paper/Archive/CVE-2026-53671

CVE-2026-53671

vbpf prevail — PREVAIL: Context-write no-op in do_mem_store allows unsafe eBPF programs to pass verification

EPSS 0.5%public exploitCVSS 9.3
critical.is priorityof 100
47
CVSS 9.3 (CNA)9.3 / 10 × 3027.9Not in CISA KEV+300.0EPSS percentile 43.3.433 × 208.7Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
prevail< 0.2.4–CNA

Scores by source

GitHub_M (CNA)9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CISA ADPSSVCExploitation: poc · Automatable: yes · Technical impact: total

References

exploitgithub.com/vbpf/prevail/security/advisories/GHSA-65rv-h458-cq99refgithub.com/vbpf/prevail/commit/de65234f67d2608b54d12571edb585ead224363crefgithub.com/vbpf/prevail/releases/tag/v0.2.4