bit7z: Path Traversal via Null Byte Injection from `gcount()` Off-by-One in `restoreSymlink()`
Published Jun 10, 2026 · Updated Nov 3, 2026
Original summary
Normalized public record · Updated Nov 3, 2026
bit7z: Path Traversal via Null Byte Injection from `gcount()` Off-by-One in `restoreSymlink()`
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
bit7z is a cross-platform C++ static library that allows the compression/extraction of archive files. Prior to version 4.0.12, a one-byte off-by-one error in SafeOutPathBuilder::restoreSymlink() allows an attacker to craft a .7z archive that, when extracted with bit7z on any non-Windows platform, creates a symlink escaping the intended output directory. Subsequent archive entries extracted through this symlink write arbitrary files outside the extraction directory with the permissions of the extracting process. This issue has been patched in version 4.0.12.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- LOW
- Confidence
- Not available
- Aliases
- None reported
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
Record history
Published Jun 10, 2026 · Last refreshed Nov 3, 2026