CVE-2026-68388

CVE CVE-2026-68388EUVD EUVD-2026-55574Published 2026-08-10T12:04:07.000Z

What the advisory describes

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.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux 966a3cb7c7db786452a87afdc3b48858fc4d4d6b <7e08ab7a061b17ac1989a225c6afb53f44a86808; patch: 7.1.6; 966a3cb7c7db786452a87afdc3b48858fc4d4d6b <a4a09e5142835633fffbde68bd0a039ba4d4bf97; 2f9f4a2d0e6fcf0673ed51195e06e47abe966900; 966a3cb7c7db786452a87afdc3b48858fc4d4d6b <b09ae45d85dc816987a71db9eebc54b0ae288e94; patch: 0; 5e397c943424de94879830e72c95f2679e297a76; c406bb9ece6ef63721daab106f132ff4b4234e81; patch: 6.18.42; 966a3cb7c7db786452a87afdc3b48858fc4d4d6b <377fe3e583e46369ee1004d5cfe12271d6589a68; 5.12.17 <5.13; 5.13.2 <5.14; patch: 6.6.148; 5.10.50 <5.11; patch: 7.2-rc4; 966a3cb7c7db786452a87afdc3b48858fc4d4d6b <437637f5ff3f573b2edf8571de91fb00a21eb4e6; patch: 6.12.101; 5.14

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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