CVE-2026-98684
Vulnérabilité non évaluée dans Linux (Linux)
Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: flush and commit data before querying allocated ranges The mode 0 / FALLOC_FL_KEEP_SIZE fallocate emulation for small interior ranges in smb3_simple_fallocate_range() issues FSCTL_QUERY_ALLOCATED_RANGES and zero-fills any sub-range the server reports as an unallocated hole, to force block allocation without changing file contents. This is unsafe against Windows servers. Per the Win32 documentation, FSCTL_QUERY_ALLOCATED_RANGES only reports ranges that *may* contain nonzero data and is explicitly not coherent with recently written data: "a call to FSCTL_QUERY_ALLOCATED_RANGES [after writing to a network file] would not necessarily return a correct list of allocated regions. To ensure coherency [...] flush the data to the file" fsx (generic/363) reproduces the resulting corruption against Windows Server 2022: a range is written, an uncached read returns the data, yet the next FSCTL_QUERY_ALLOCATED_RANGES on that range reports it as a whole hole, so the emulation overwrites live data with zeroes. A network trace confirmed the WRITE, the READ returning data and the query returning an empty range list within microseconds. Samba does not exhibit this; its query is coherent with the written data. Write back the dirty pages, drain any outstanding I/O and issue an SMB2 FLUSH to force the server to commit the data before querying the allocated ranges, so the query reflects the data actually present. With this, generic/363 passes against both Windows Server 2022 and Samba over 100000 fsx operations.
Gravité et risque d'exploitation
CVE-2026-98684 obtient un score CVSS de 0.0/10, soit une gravité non évaluée.
Que faire ?
- Vérifiez si Linux (versions <5.11, 5.13.2, <5.13, <aa994489bd835547c191827acc460192e147032d, 0, <f82242fe3109a3ef72f429540b5bdde08fbfb0e4, 7.2.10, <5.14, 5e397c943424de94879830e72c95f2679e297a76, 966a3cb7c7db786452a87afdc3b48858fc4d4d6b, 5.14, <bf84e44ff0ed802778eafd7ecb623635379cb506, 2f9f4a2d0e6fcf0673ed51195e06e47abe966900, <=6.18.*, <=7.2.*, <=*, 5.12.17, 6.18.56, c406bb9ece6ef63721daab106f132ff4b4234e81, 5.10.50, 7.3) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.