# CVE-2026-99272: Linux kernel SMB2 client buffer over-read in SMB2_read()

Source: https://junglewise.ai/threats/cve-2026-99272-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-2026-99272 · Severity: info · Published 2026-11-07

The Linux kernel's SMB2 client implementation contains a buffer over-read vulnerability in the SMB2_read() function used for reading files from SMB servers. A malicious SMB server can craft a specially crafted READ response that causes the client to copy data beyond the bounds of the received buffer, potentially exposing sensitive kernel memory or causing a system crash.

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

## Quick answers

**Is CVE-2026-99272 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99272 being exploited in the wild.

**How severe is CVE-2026-99272?** Informational severity, published 7 November 2026.

**Which products and versions are affected?** Linux Kernel All versions with SMB2 client support.

**Is there a fix for CVE-2026-99272?** Yes: fixed in Resolved by validation in SMB2_read() ensuring DataOffset and DataLength fit within response bounds (commit 2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1). Until then: Restrict SMB client access to trusted SMB servers only; disable SMB2 support if not required for business operations. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-99272 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-99272?** 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.

## How to fix

- Fixed in Resolved by validation in SMB2_read() ensuring DataOffset and DataLength fit within response bounds (commit 2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1)

Restrict SMB client access to trusted SMB servers only; disable SMB2 support if not required for business operations.

## Technical details

The SMB2_read() function fails to validate that the DataOffset and DataLength fields from the server response stay within the bounds of the actual response buffer (rsp_iov.iov_len). An attacker controlling an SMB server can send a READ response with DataOffset=0 and an inflated DataLength value, causing the client to attempt to copy data from addresses beyond the 448-byte receive buffer—up to 16 KiB in general cases. This results in a kernel heap buffer over-read (KASAN-detectable slab-out-of-bounds).

## Affected products

- Linux Linux kernel All versions with SMB2 client support

## Timeline

- 2026-11-07: disclosed

## References

- [https://git.kernel.org/stable/c/1ba1937de005e261a8858f45bfef5da7458df94c](https://git.kernel.org/stable/c/1ba1937de005e261a8858f45bfef5da7458df94c)
- [https://git.kernel.org/stable/c/2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1](https://git.kernel.org/stable/c/2ec9cdf469dd32bcf33073aeb30c08e9356e0ca1)

## Related threats

- [Linux IOMMU page table logic error in arm_lpae_split_blk_unmap](https://junglewise.ai/threats/cve-2026-56934-in-arm-lpae-split-blk-unmap-of-drivers-iommu-io-pgtable-arm)
- [Linux kernel null pointer dereference in TCP established lookup](https://junglewise.ai/threats/cve-2026-99288-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel xen-netback race condition in XenBus disconnect](https://junglewise.ai/threats/cve-2026-99286-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel shared-frag flag loss in skb_zerocopy](https://junglewise.ai/threats/cve-2026-99284-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)
- [Linux kernel netfilter conntrack TCP RST timeout handling](https://junglewise.ai/threats/cve-2026-99283-in-the-linux-kernel-the-following-vulnerability-has-been-resolved)