Out-of-bounds write in Linux kernel - CVE-2026-99083

Vulnerability details

The vulnerability allows a remote attacker to corrupt kernel heap memory and potentially cause a denial of service.

The vulnerability exists due to an out-of-bounds write in the Linux kernel ksmbd krb5_authenticate() function when processing SMB2_SESSION_SETUP as a non-first element of a compounded SMB2 request. A remote attacker can send a specially crafted compounded request to trigger an overstated response buffer capacity calculation, allowing a Kerberos AP-REP token to be copied beyond response_buf into adjacent kernel heap memory.

Affected software

How to mitigate CVE-2026-99083

External References

• https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0
• https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23
• https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06
• https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059
• https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a

Related Security Bulletins

• Out-of-bounds write in Linux kernel smb server
• Debian update for linux