CVE-2026-68229 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
media: cedrus: skip invalid H.264 reference list entries
Cedrus consumes H.264 ref_pic_list0/ref_pic_list1 entries from the stateless slice control and later uses their indices to look up decode->dpb[] in _cedrus_write_ref_list().
Rejecting such controls in cedrus_try_ctrl() would break existing userspace, since stateless H.264 reference lists may legitimately carry out-of-range indices for missing references. Instead, guard the actual DPB lookup in Cedrus and skip entries whose indices do not fit the fixed V4L2_H264_NUM_DPB_ENTRIES array.
This keeps the fix local to the driver use site and avoids out-of-bounds reads from malformed or unsupported reference list entries.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability in question affects the Linux kernel's cedrus driver, which handles hardware video decoding operations for H.264 video streams. This specific issue relates to how the driver processes reference picture lists within H.264 stateless slice control structures. The flaw occurs when the cedrus driver consumes ref_pic_list0 and ref_pic_list1 entries from these control structures and subsequently uses their indices to access decode->dpb[] arrays during video decoding operations. This represents a classic buffer over-read vulnerability that could potentially lead to system instability or information disclosure.
The technical implementation of this vulnerability stems from insufficient validation of reference list entries before they are used in array lookups. When processing H.264 video streams, the cedrus driver directly translates indices from stateless slice control structures into array offsets without proper bounds checking against the fixed V4L2_H264_NUM_DPB_ENTRIES limit. This design flaw allows malicious or malformed input data to specify reference list entries that exceed the allocated DPB (Decoded Picture Buffer) array boundaries, creating opportunities for out-of-bounds memory access patterns.
From an operational perspective, this vulnerability demonstrates a critical security weakness in multimedia processing drivers where user-space applications provide potentially untrusted input data. The fix implemented addresses this by introducing defensive programming practices at the point of actual array access rather than attempting to reject inputs at the control validation layer. This approach maintains backward compatibility with existing userspace applications while preventing the out-of-bounds memory reads that could occur when processing malformed reference list entries.
The mitigation strategy employed aligns with secure coding principles and follows established best practices for handling untrusted input in kernel space drivers. By placing the bounds checking directly at the DPB lookup point, the solution prevents the specific out-of-bounds read conditions while preserving existing functionality. This approach corresponds to CWE-129: Improper Validation of Array Index and demonstrates adherence to the principle of least privilege in kernel driver development.
The vulnerability has implications for the broader multimedia processing ecosystem within Linux systems, particularly affecting embedded devices and media servers that rely on hardware-accelerated video decoding. The ATT&CK framework categorizes this under privilege escalation through kernel vulnerabilities, as successful exploitation could potentially allow attackers to access sensitive system information or cause denial of service conditions. The fix maintains system stability while ensuring that malformed video streams cannot trigger memory corruption in the kernel space driver components.
This remediation approach reflects industry standards for kernel security hardening, where defensive programming techniques are applied at the point of use rather than attempting to prevent all potential malicious inputs at earlier validation stages. The solution effectively addresses the root cause without breaking existing functionality, demonstrating proper risk management in kernel driver development practices and maintaining compatibility with legitimate userspace applications that may legitimately provide reference list entries with out-of-range indices for missing references.