CVE-2026-64380 PUBLISHED

smb: client: harden POSIX SID length parsing

Assigner: Linux
Reserved: 19.07.2026 Published: 25.07.2026 Updated: 25.07.2026

In the Linux kernel, the following vulnerability has been resolved:

smb: client: harden POSIX SID length parsing

posix_info_sid_size() reads sid[1] to obtain the subauthority count, but its existing boundary check still accepts buffers with only one remaining byte. Require two bytes before reading sid[1] so all client paths that reuse the helper reject truncated POSIX SIDs safely.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 171605aed68380c2fa75dff9b3a1ed427c50065b (excl.)
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 4213c1208978483021d7d125c131de3985d38f61 (excl.)
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 96e889bc1e759c83f25093e8c2f3da31b4973f30 (excl.)
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 0de5b8e76847f5de26f364a82c6602c4881c30da (excl.)
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 427eb7eb46425fec845a43e861f3d6e2899cae59 (excl.)
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 86c5d470f5d42e61123b2f4b4f0b91f4eee5b980 (excl.)
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 46a84715a015cb48e1b9c219dc88c03d8a541ea4 (excl.)
  • affected from 349e13ad30b45998bb9937cfe0b32be6f951976d to 7ad2bcf2441430bb2e918fb3ef9a90d775a6e422 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 5.7 is affected
  • unaffected from 0 to 5.7 (excl.)
  • unaffected from 5.10.261 to 5.10.* (incl.)
  • unaffected from 5.15.212 to 5.15.* (incl.)
  • unaffected from 6.1.178 to 6.1.* (incl.)
  • unaffected from 6.6.145 to 6.6.* (incl.)
  • unaffected from 6.12.96 to 6.12.* (incl.)
  • unaffected from 6.18.39 to 6.18.* (incl.)
  • unaffected from 7.1.4 to 7.1.* (incl.)
  • unaffected from 7.2-rc2 to * (incl.)

References