Pre-authentication kernel memory corruption via signed comparison
Published May 6, 2026 · Updated May 6, 2026
Heap buffer overflow in Linux Kernel ksmbd allows remote attackers to corrupt kernel memory through unauthenticated SMB Direct negotiation. The smb_direct_prepare_negotiation() function compares attacker-controlled 32-bit receive sizes with min_t(int), so 0x80000000 becomes negative and selects an undersized receive buffer. An unauthenticated RDMA peer can follow the crafted negotiation with a message larger than 1420 bytes, causing an out-of-bounds DMA write that can panic the kernel or corrupt its control data.
Summary
What happened
Heap buffer overflow in Linux Kernel ksmbd allows remote attackers to corrupt kernel memory through unauthenticated SMB Direct negotiation. The smb_direct_prepare_negotiation() function compares attacker-controlled 32-bit receive sizes with min_t(int), so 0x80000000 becomes negative and selects an undersized receive buffer. An unauthenticated RDMA peer can follow the crafted negotiation with a message larger than 1420 bytes, causing an out-of-bounds DMA write that can panic the kernel or corrupt its control data.
The record
- CVE
- CVE-2026-43185
- Published
- May 6, 2026
- Updated
- May 6, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-674, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 6, 2026CVE publishedPublication date reported by the CVE source.
- May 6, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <55abc475d096da4a5356b6efb0cfdc6156bc1550
- Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <6b4f875aac344cdd52a1f34cc70ed2f874a65757
- Affected versionversion=0626e6641f6b467447c81dd7678a69c66f7746cf <ceae058eb707ddd0d68f0872f9d9f23b7c30c37b
- Affected versionversion=5.15
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo