Memory disclosure via overlapping SMB allocation ranges
Published Aug 10, 2026 · Updated Aug 10, 2026
Out-of-bounds read in the Linux kernel SMB client allows remote attackers to disclose memory via malformed allocated-range replies. smb3_simple_fallocate_range() advances by the server's full range length rather than only the overlap, skipping zero-fill and permitting an oversized length to read past its zero buffer. Exploitation requires a Linux client to process crafted range data from an SMB server; consequences include kernel-memory disclosure, file-data corruption, and system instability.
Summary
What happened
Out-of-bounds read in the Linux kernel SMB client allows remote attackers to disclose memory via malformed allocated-range replies. smb3_simple_fallocate_range() advances by the server's full range length rather than only the overlap, skipping zero-fill and permitting an oversized length to read past its zero buffer. Exploitation requires a Linux client to process crafted range data from an SMB server; consequences include kernel-memory disclosure, file-data corruption, and system instability.
The record
- CVE
- CVE-2026-68388
- Published
- Aug 10, 2026
- Updated
- Aug 10, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- CWE-131
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 10, 2026CVE publishedPublication date reported by the CVE source.
- Aug 10, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=2f9f4a2d0e6fcf0673ed51195e06e47abe966900
- Affected versionversion=5.10.50 <5.11
- Affected versionversion=5.12.17 <5.13
- Affected versionversion=5.13.2 <5.14
- Affected versionversion=5.14
- Affected versionversion=5e397c943424de94879830e72c95f2679e297a76
- Affected versionversion=966a3cb7c7db786452a87afdc3b48858fc4d4d6b <377fe3e583e46369ee1004d5cfe12271d6589a68
- Affected versionversion=966a3cb7c7db786452a87afdc3b48858fc4d4d6b <437637f5ff3f573b2edf8571de91fb00a21eb4e6
- Affected versionversion=966a3cb7c7db786452a87afdc3b48858fc4d4d6b <7e08ab7a061b17ac1989a225c6afb53f44a86808
- Affected versionversion=966a3cb7c7db786452a87afdc3b48858fc4d4d6b <a4a09e5142835633fffbde68bd0a039ba4d4bf97
- Affected versionversion=966a3cb7c7db786452a87afdc3b48858fc4d4d6b <b09ae45d85dc816987a71db9eebc54b0ae288e94
- Affected versionversion=c406bb9ece6ef63721daab106f132ff4b4234e81
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
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Technologies
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