CVE-2026-23318

In the Linux kernel, the following vulnerability has been resolved:

ALSA: usb-audio: Use correct version for UAC3 header validation

The entry of the validators table for UAC3 AC header descriptor is defined with the wrong protocol version UAC_VERSION_2, while it should have been UAC_VERSION_3. This results in the validator never matching for actual UAC3 devices (protocol == UAC_VERSION_3), causing their header descriptors to bypass validation entirely. A malicious USB device presenting a truncated UAC3 header could exploit this to cause out-of-bounds reads when the driver later accesses unvalidated descriptor fields.

The bug was introduced in the same commit as the recently fixed UAC3 feature unit sub-type typo, and appears to be from the same copy-paste error when the UAC3 section was created from the UAC2 section.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/0dcd1ed96c03459cf14706885c9dd3c1fd8bd29f
• https://git.kernel.org/stable/c/1e5753ff4c2e86aa88516f97a224c90a3d0b133e
• https://git.kernel.org/stable/c/499ffd15b00dc91ac95c28f76959dfb5cdcc84d5
• https://git.kernel.org/stable/c/54f9d645a5453d0bfece0c465d34aaf072ea99fa
• https://git.kernel.org/stable/c/82a7d0a1b88798de1a609130080ce0c65dd869e9
• https://git.kernel.org/stable/c/8307d93e63d5f54ef10412d4db2dd551e920dee4
• https://git.kernel.org/stable/c/a0c6ae2ea84528f198bf7fd0117f12fd0cf6d7cc
• https://git.kernel.org/stable/c/d3904ca40515272681ae61ad6f561c24f190957f