CVE-2026-43185

ksmbd: fix signededness bug in smb_direct_prepare_negotiation()

State
Published
Severity
9.8 Critical
Published
May 6, 2026
Updated
Oct 30, 2026
Reserved
May 1, 2026

Read the record on cve.org

Description

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

ksmbd: fix signededness bug in smb_direct_prepare_negotiation()

smb_direct_prepare_negotiation() casts an unsigned __u32 value from sp->max_recv_size and req->preferred_send_size to a signed int before computing min_t(int, ...). A maliciously provided preferred_send_size of 0x80000000 will return as smaller than max_recv_size, and then be used to set the maximum allowed alowed receive size for the next message.

By sending a second message with a large value (>1420 bytes) the attacker can then achieve a heap buffer overflow.

This fix replaces min_t(int, ...) with min_t(u32)

Scores

CVSSScoreVectorSource
3.19.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HLinux

Weaknesses

The record names no weakness.

Affected Products

ProductVersions
LinuxLinux
  • 0626e6641f6b467447c81dd7678a69c66f7746cf to before 1c268fd2f59dc9ccb2c2a7d1f439b232dbe1c06cAffected
  • 0626e6641f6b467447c81dd7678a69c66f7746cf to before 56eab82fa6fb5ca024b0514e249d40d9b23ee5a7Affected
  • 0626e6641f6b467447c81dd7678a69c66f7746cf to before a110dbe928561d440e9e117d17331139a0bedaceAffected
  • 0626e6641f6b467447c81dd7678a69c66f7746cf to before ceae058eb707ddd0d68f0872f9d9f23b7c30c37bAffected
  • 0626e6641f6b467447c81dd7678a69c66f7746cf to before 55abc475d096da4a5356b6efb0cfdc6156bc1550Affected
  • 0626e6641f6b467447c81dd7678a69c66f7746cf to before 6b4f875aac344cdd52a1f34cc70ed2f874a65757Affected
LinuxLinux
  • 5.15Affected
  • before 5.15Not affected
  • 6.1.191 through 6.1.*Not affected
  • 6.6.160 through 6.6.*Not affected
  • 6.12.114 through 6.12.*Not affected
  • 6.18.16 through 6.18.*Not affected
  • 6.19.6 through 6.19.*Not affected
  • 7.0 and laterNot affected

References

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