CVE-2026-74295 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
ASoC: codecs: hdac_hdmi: Validate written enum value
hdac_hdmi_set_pin_port_mux() uses the written enum value to index the texts array before calling snd_soc_dapm_put_enum_double(), which validates that the value is within the enum item range.
An out-of-range value can therefore make the driver read past the texts array before the helper rejects the write. Move the lookup after the helper has accepted the value.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability in question affects the Linux kernel's sound subsystem specifically within the hdac_hdmi codec driver component. This issue represents a classic buffer over-read condition that occurs during the handling of audio pin configuration operations. The problem manifests when the hdac_hdmi_set_pin_port_mux() function processes enumerated values for configuring HDMI audio pin mappings, where improper validation order creates a window for memory access violations.
The technical flaw stems from the incorrect sequence of validation operations within the driver's control flow. When a user attempts to set a pin port multiplexer configuration, the function first uses the provided enum value as an index into the texts array without prior validation. Only after this potentially unsafe array access does the function call snd_soc_dapm_put_enum_double() which performs the legitimate range checking. This ordering creates a race condition where malicious or malformed input can cause the driver to read beyond the bounds of the allocated texts array before the validation mechanism has an opportunity to reject the invalid value.
This vulnerability directly relates to CWE-129, which addresses improper validation of array indices, and can be categorized under ATT&CK technique T1068 for local privilege escalation through kernel exploits. The operational impact extends beyond simple memory corruption as it could potentially enable attackers to read sensitive kernel memory locations or cause system instability through controlled memory access violations.
The security implications are particularly concerning in embedded systems and servers where HDMI audio interfaces may be exposed to untrusted users or network-based attacks. An attacker who can influence the pin port multiplexer configuration could potentially extract kernel memory contents, leading to information disclosure vulnerabilities that might reveal kernel addresses, credential storage locations, or other sensitive data structures. The vulnerability is especially dangerous because it operates at the kernel level within a critical subsystem responsible for audio device management.
Mitigation strategies should focus on ensuring proper validation ordering within the driver code, moving the enum lookup operation after the validation helper has confirmed the value's legitimacy. System administrators should apply the latest kernel patches that correct this validation sequence and implement proper access controls to limit who can modify audio pin configurations. Additionally, monitoring for unusual patterns in audio subsystem calls and implementing kernel hardening measures such as stack canaries and address space layout randomization can provide additional defense-in-depth layers against exploitation attempts.