Critical severity · published May 6, 2026
CVE-2026-43185
ksmbd: fix signededness bug in smb_direct_prepare_negotiation()
9.8
CVSS
0.8%
EPSS
No
On KEV
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)
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 57% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
5.15 before 6.18.16; 6.19 before 6.19.6; 7.0 · source: NVD
LI
Linux · Linux
0626e6641f6b467447c81dd7678a69c66f7746cf before 56eab82fa6fb5ca024b0514e249d40d9b23ee5a7; 0626e6641f6b467447c81dd7678a69c66f7746cf before a110dbe928561d440e9e117d17331139a0bedace; 0626e6641f6b467447c81dd7678a69c66f7746cf before ceae058eb707ddd0d68f0872f9d9f23b7c30c37b; 0626e6641f6b467447c81dd7678a69c66f7746cf before 55abc475d096da4a5356b6efb0cfdc6156bc1550; 0626e6641f6b467447c81dd7678a69c66f7746cf before 6b4f875aac344cdd52a1f34cc70ed2f874a65757; 5.15 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-43185
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-43185
Patch
https://git.kernel.org/stable/c/55abc475d096da4a5356b6efb0cfdc6156bc1550
git.kernel.org
https://git.kernel.org/stable/c/56eab82fa6fb5ca024b0514e249d40d9b23ee5a7
Patch
https://git.kernel.org/stable/c/6b4f875aac344cdd52a1f34cc70ed2f874a65757
git.kernel.org
https://git.kernel.org/stable/c/a110dbe928561d440e9e117d17331139a0bedace
Patch
https://git.kernel.org/stable/c/ceae058eb707ddd0d68f0872f9d9f23b7c30c37b
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