smb/client: handle overlapping allocated ranges in fallocate
Summary
| CVE | CVE-2026-68388 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-10 13:20:32 UTC |
| Updated | 2026-08-19 17:20:47 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: smb/client: handle overlapping allocated ranges in fallocate smb3_simple_fallocate_range() can skip holes when an allocated range returned by the server starts before the current fallocate offset. The skipped hole is not zero-filled, but fallocate still returns success. A later write to that hole may therefore fail with ENOSPC. The function queries allocated ranges so that it can preserve existing contents and write zeroes only into holes. However, the server may return a range that starts before the current fallocate offset. For example, assume the fallocate request is [100, 400) and the only allocated range returned by the server is [0, 200): Request: [100, 400) Server range: [ 0, 200) allocated Correct: [100, 200) allocated data, skip [200, 400) hole, zero-fill Current: [100, 300) skipped [300, 400) zero-filled afterwards The current code adds the full server range length, 200, to the current offset 100 and moves to 300. As a result, the hole in [200, 300) is skipped without being zero-filled. Fix this by advancing only over the part of the allocated range that overlaps the current fallocate offset. Ignore ranges that end before the current offset and reject ranges whose end offset overflows. This also prevents a malformed range length from causing an out-of-bounds zero-buffer read. |
Risk And Classification
Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.004630000 probability, percentile 0.384410000 (date 2026-08-19)
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | Secondary | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | DECLARED | 9.8 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected c406bb9ece6ef63721daab106f132ff4b4234e81 aeb58a4eb39a7ff4d7782b4f4ada0fda5e0675d2 git | Not specified |
| CNA | Linux | Linux | affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b 01719883235507b1585e4c51e320d9a7113dc698 git | Not specified |
| CNA | Linux | Linux | affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b f47c7277c03a636fcc3a57969f2dc09567b3c050 git | Not specified |
| CNA | Linux | Linux | affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b 437637f5ff3f573b2edf8571de91fb00a21eb4e6 git | Not specified |
| CNA | Linux | Linux | affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b 377fe3e583e46369ee1004d5cfe12271d6589a68 git | Not specified |
| CNA | Linux | Linux | affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b 7e08ab7a061b17ac1989a225c6afb53f44a86808 git | Not specified |
| CNA | Linux | Linux | affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b a4a09e5142835633fffbde68bd0a039ba4d4bf97 git | Not specified |
| CNA | Linux | Linux | affected 966a3cb7c7db786452a87afdc3b48858fc4d4d6b b09ae45d85dc816987a71db9eebc54b0ae288e94 git | Not specified |
| CNA | Linux | Linux | affected 2f9f4a2d0e6fcf0673ed51195e06e47abe966900 git | Not specified |
| CNA | Linux | Linux | affected 5e397c943424de94879830e72c95f2679e297a76 git | Not specified |
| CNA | Linux | Linux | affected 5.10.50 5.10.265 semver | Not specified |
| CNA | Linux | Linux | affected 5.12.17 5.13 semver | Not specified |
| CNA | Linux | Linux | affected 5.13.2 5.14 semver | Not specified |
| CNA | Linux | Linux | affected 5.14 | Not specified |
| CNA | Linux | Linux | unaffected 5.14 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.265 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.216 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.183 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.148 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.101 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.42 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.6 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/f47c7277c03a636fcc3a57969f2dc09567b3c050 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/b09ae45d85dc816987a71db9eebc54b0ae288e94 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/01719883235507b1585e4c51e320d9a7113dc698 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/aeb58a4eb39a7ff4d7782b4f4ada0fda5e0675d2 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/a4a09e5142835633fffbde68bd0a039ba4d4bf97 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/7e08ab7a061b17ac1989a225c6afb53f44a86808 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/377fe3e583e46369ee1004d5cfe12271d6589a68 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/437637f5ff3f573b2edf8571de91fb00a21eb4e6 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.