# CVE-2026-99273: Linux kernel ksmbd buffer overflow in stream info

Source: https://junglewise.ai/threats/cve-2026-99273-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-07. Updated: 2026-11-07  
License: CC BY 4.0 with a link back

CVE-2026-99273 · Severity: info · Published 2026-11-07

The Linux kernel's ksmbd SMB server implementation contains a buffer overflow in its handling of file stream information. When processing SMB2 file stream requests, the code fails to account for a UTF-16 string terminator, causing writes past the end of an allocated 448-byte response buffer. An attacker with SMB access could crash the system or potentially execute code.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-99273 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99273 being exploited in the wild.

**How severe is CVE-2026-99273?** Informational severity, published 7 November 2026.

**Which products and versions are affected?** Linux Kernel versions prior to commit a025c4991a7d83edc4dd339e3ea86d8ff6226eca.

**Is there a fix for CVE-2026-99273?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-99273 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-99273?** Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The get_file_stream_info() function in fs/smb/server/smb2pdu.c miscalculates buffer space required for SMB2 stream name responses. The smbConvertToUTF16() function always appends a two-byte UTF-16 null terminator, but the budget checks reserve space only for the converted characters. When a stream entry exactly fills the small response buffer, the terminator writes two bytes past the allocated heap, causing a heap buffer overflow. This is a local or network attack via SMB protocol requiring file access permissions.

## Affected products

- Linux Linux kernel versions prior to commit a025c4991a7d83edc4dd339e3ea86d8ff6226eca

## Timeline

- 2026-11-07: disclosed

## References

- [https://git.kernel.org/stable/c/06a751809ebd33e95b05bf733697318a17a4872b](https://git.kernel.org/stable/c/06a751809ebd33e95b05bf733697318a17a4872b)
- [https://git.kernel.org/stable/c/0e64f89563164719ceb1aa33f2a8bfd6391fa340](https://git.kernel.org/stable/c/0e64f89563164719ceb1aa33f2a8bfd6391fa340)

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