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TI-2026-38710 Aliases CVE-2026-53671

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

Priority HIGH 81CWE-682Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00507 43rd percentileScored 2026-11-07
Fix Fixed prevail (vbpf): 0.2.4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
vbpfprevailbefore 0.2.40.2.4Patch availableCNA
  • prevail Vendorvbpf Affected before 0.2.4 Fixed in 0.2.4 Patch available CNA

Remediation

  • Fix · CNA prevail (vbpf) Fixed in 0.2.4

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-53671

References

Other 3

  • TI-2026-38709 PREVAIL: Non-singleton typeset in add() skips offset update, allowing OOB access to pass eBPF verification CVSS 4.0CRITICAL 9.3
  • TI-2026-38729 PREVAIL: ALU32 pointer arithmetic accepted without is64 gate — verifier emits false PASS for pointer-corrupting programs CVSS 4.0HIGH 8.8

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences