PREVAIL: ALU32 pointer arithmetic accepted without is64 gate — verifier emits false PASS for pointer-corrupting programs
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 0.2.4
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: total
Summary
PREVAIL is a Polynomial-Runtime EBPF Verifier using an Abstract Interpretation Layer. Prior to version 0.2.4, the prevail eBPF verifier accepts ALU32 ADD and SUB instructions that operate on pointer-typed registers without checking the is64 flag. Because ALU32 arithmetic zero-extends the 32-bit result, the upper half of any pointer is silently destroyed at runtime, yet prevail marks the program as verified safe. Any caller that can submit an eBPF program for verification — including unprivileged users on kernels that permit BPF program loading — can produce a program that passes verification but faults or misbehaves at runtime. This issue has been patched in version 0.2.4.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: total
- Record last updated
Affected versions
- vbpf prevail
fixed in 0.2.4