Stack-data disclosure via unbounded ZealFS bitmap loop
Published May 12, 2026 · Updated May 12, 2026
Out-of-bounds read in NanaZip's ZealFS parser allows attackers to disclose stack data by opening a crafted ZealFS v1 image. Zealfs::Open accepts BitmapSize values up to 255 for the 32-byte PagesBitmap array, then uses that field as the loop bound and reads past the stack header. Opening the image is required; the overread exposes adjacent stack bytes through the free-space property or crashes the process.
Summary
What happened
Out-of-bounds read in NanaZip's ZealFS parser allows attackers to disclose stack data by opening a crafted ZealFS v1 image. Zealfs::Open accepts BitmapSize values up to 255 for the 32-byte PagesBitmap array, then uses that field as the loop bound and reads past the stack header. Opening the image is required; the overread exposes adjacent stack bytes through the free-space property or crashes the process.
The record
- CVE
- CVE-2026-42446
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- M2-Team
- Product
- NanaZip
- Classifications
- CWE-125, T1204.002
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=>= 5.0.1250.0, < 6.0.1698.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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