Bug 2555085 (CVE-2026-98711)

Summary: CVE-2026-98711 kernel: kernel: cw1200: Information disclosure via out-of-bounds read during frame transmission
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's cw1200 wireless network driver. During data transmission, the driver pads transfer sizes to meet hardware alignment requirements without reserving sufficient space in the frame buffer. This causes the driver to read beyond the buffer boundaries and transmit adjacent kernel memory across the bus. Consequently, a rogue or compromised hardware device can capture sensitive kernel heap data, leading to information disclosure.
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Description OSIDB Bzimport 2026-10-18 15:53:33 UTC 
In the Linux kernel, the following vulnerability has been resolved:

wifi: cw1200: fix TX padding OOB read leaking heap data to device

The TX path rounds the transfer size up to the bus alignment
(align_size(), up to 511 bytes for SDIO, 1 byte for SPI) but sends
the padded length straight from the frame buffer, which has no room
reserved for the padding.  cw1200_data_write() therefore reads past
the end of the frame and the bus transfer carries those bytes to the
device.  A bogus device can collect up to 511 bytes of kernel heap
data per TX frame.

The RX path does not have this problem: it allocates the skb with
the aligned length (alloc_len) before reading.

Compute the exact padding with the bus align_size() callback, make
sure queued TX frames have tailroom for it, and zero the padding
bytes before the transfer so nothing past the frame is exposed.

This is not expected to change driver behavior on most cases: frame
contents and transfer sizes are unchanged, only the content of the
padding bytes (previously undefined stale memory, now zero), which
the device never reads since the WSM header carries the real frame
length.  The skb expansion can only fail under memory exhaustion,
in which case the frame is dropped like on the existing error paths
of cw1200_tx().

Discovered by Atuin - Automated Vulnerability Discovery Engine.