CVE-2026-68279
Received Received - Intake

Out-of-Bounds Read in Linux Kernel DRM DP MST

Publication date: 2026-08-10

Last updated on: 2026-08-10

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: drm/dp/mst: fix OOB reads in remote DPCD/I2C sideband reply parsers drm_dp_sideband_parse_remote_dpcd_read() reads num_bytes from the raw message and then unconditionally does: memcpy(bytes, &raw->msg[idx], num_bytes); without checking that idx + num_bytes <= raw->curlen. raw->msg[] is 256 bytes; if a malicious or misbehaving MST hub sets num_bytes larger than the remaining payload, the memcpy reads past the received data into whatever follows in raw->msg[]. drm_dp_sideband_parse_remote_i2c_read_ack() has the same flaw (noted with a /* TODO check */ comment since the code was introduced). Fix both functions by using a single combined check (idx + num_bytes > curlen) before each memcpy. Since num_bytes is u8, it is always >= 0, so this strictly subsumes the simpler idx > curlen form and no separate step is needed. [added missing fixes tag]

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Meta Information

Published
2026-08-10
Last Modified
2026-08-10
Generated
2026-08-10
AI Q&A
2026-08-10
EPSS Evaluated
N/A
NVD
CVE-2026-68279
EUVD
EUVD-2026-55380

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a vulnerability in the Linux kernel's DisplayPort Multi-Stream Transport (MST) handling. It involves out-of-bounds (OOB) memory reads in functions that parse remote DPCD/I2C sideband replies. The issue occurs when the code copies data without verifying if the requested size fits within the available buffer, potentially reading past the end of the buffer into adjacent memory.

Detection Guidance

This vulnerability involves out-of-bounds reads in the Linux kernel's DisplayPort MST (Multi-Stream Transport) sideband message parsers. Detection requires checking for kernel logs or crashes related to drm_dp_sideband_parse_remote_dpcd_read or drm_dp_sideband_parse_remote_i2c_read_ack functions. Use commands like dmesg | grep -i drm or journalctl -k | grep -i drm to inspect kernel logs for suspicious activity.

Impact Analysis

If exploited, this vulnerability could allow an attacker with access to a malicious or misbehaving MST hub to read sensitive kernel memory. This might lead to information disclosure, privilege escalation, or system instability. The impact depends on the kernel's memory layout and the attacker's capabilities.

Mitigation Strategies

Immediately update your Linux kernel to the latest patched version provided by your distribution. If immediate patching is not possible, consider disabling DisplayPort MST functionality temporarily by blacklisting the drm_kms_helper module or restricting access to affected systems until the update is applied.

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