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In October, several unpatched Linux vulnerabilities were disclosed on public mailing lists, revealing technical details before fixes were widely available.

These disclosures included two critical flaws in KSMBD that could let remote attackers execute code, along with reports of privilege escalation and information disclosure.

Trend Micro’s Zero Day Initiative (ZDI) submitted the reports, prompting Linux kernel maintainer Greg Kroah-Hartman to question why these vulnerabilities were published without accompanying patches. However, it remains unconfirmed whether the disclosures were accidental.

The reports credit Trend Micro’s AI scanner for identifying the vulnerabilities, while updated kernel guidance suggests that AI-discovered bugs are treated as already public. As of October 23, 2026, ZDI had not publicly clarified its submission decisions.

According to CSN, the two most severe vulnerabilities affect KSMBD, the optional SMB file server in the Linux kernel. KSMBD is distinct from Samba, so systems using Samba alone are not automatically affected by these issues.

  1. ZDI-CAN-33774: Rated CVSS 9.0, this vulnerability involves a race condition with queued network requests. The disclosure indicates that inconsistent request handling could lead to out-of-bounds memory access, potentially enabling remote code execution.
  2. ZDI-CAN-33549: Also rated CVSS 9.0, this issue affects KSMBD’s SMB Direct implementation. An integer underflow can produce an incorrect length value, causing subsequent memory operations to exceed buffer limits. Exposure depends on the server’s configuration and whether SMB Direct functionality is enabled.

A fix for the second vulnerability is reportedly available in a development branch targeting Linux 7.5. However, the existence of a fix in a development branch does not guarantee that released kernels or distribution packages contain this correction.

At the time of reporting, neither critical vulnerability had a fix identified in the mainline kernel or its integration tree, nor had they been assigned a CVE identifier.

There are four other disclosures detailing different attack surfaces:

  • ZDI-CAN-33367: Involves the skb_zerocopy networking code and could enable local privilege escalation. Developers have reportedly received an independent report earlier and are working on a patch.
  • ZDI-CAN-34068: Concerns an out-of-bounds write in the VMware graphics driver, potentially allowing a local attacker to elevate privileges.
  • ZDI-CAN-34076: Describes an uninitialized resource in the NVMe over Fabrics target implementation, which could lead to information exposure.
  • ZDI-CAN-32005: Addresses a stack-buffer overflow in ConnMan’s handling of search-domain TCP queries. ConnMan is a user-space network management service and not a kernel component.

Administrators should first check whether KSMBD is enabled and assess whether it’s necessary. Disabling unused KSMBD functionality can help minimize exposure to the reported remote-code-execution vulnerabilities.

If KSMBD is required, restrict file-sharing access to trusted networks, review share permissions, and evaluate SMB Direct exposure. Monitor distribution security advisories instead of assuming upstream development changes have been applied to deployed systems.

While public technical details can help defenders, they can also give attackers information before patches are available. Therefore, apply vendor-approved updates promptly; relying solely on network restrictions is not a substitute for proper fixes.

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