Cloudanix VulnDB

CVE-2026-93122

High · 7.8

CVSS

7.8

EPSS

0.2%

Published

Sep 17, 2026

CISA due date

—

Cloudanix analysis

Schedule a fix SSVC: Track

A flaw in how the Linux kernel handles USB audio gadget settings lets a local user send too many numbers and overwrite memory, which could let them take control of the system.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Low
Impact
Full Compromise
Component
OS kernel
Class
Buffer Overflow
Remediation
Patch
Effort
Low
Patch risk
Low

What it actually does

Out-of-bounds write in Linux kernel USB gadget UAC1/UAC2 configfs rate-list parsers: comma-separated token count exceeding UAC_MAX_RATES (10) overwrites past the end of p_srates[] or c_srates[] arrays in f_uac1_opts/f_uac2_opts without bounds checking.

Why it matters to the business

Local attackers can corrupt kernel memory on systems exposing USB audio gadget configuration interfaces, potentially leading to privilege escalation or denial of service on affected Linux hosts.

How an attack unfolds

An attacker with local access writes an 11+ entry comma-separated sampling-rate list to a UAC1 or UAC2 p_srate or c_srate configfs attribute; the store handler parses beyond the fixed array size, performing an out-of-bounds write that may be observed under UBSAN or used for memory corruption.

How to fix it

Apply the upstream fix that caps parsed tokens at UAC_MAX_RATES, preserves the original kstrdup pointer for kfree, and rejects excess entries; rebuild and boot the patched kernel.

How to confirm the fix worked

Confirm the patched kernel source contains the rate-list length check before the loop and the retained kstrdup pointer; attempt to store 11 rates and verify no UBSAN report or kernel oops occurs.

Typical attack path

  1. Obtain local shell or write access on a Linux system exposing USB gadget configfs
  2. Locate UAC1 or UAC2 function configfs directory
  3. Echo a comma-separated list containing more than 10 sampling rates into the p_srate or c_srate attribute
  4. Trigger the store handler to perform the out-of-bounds write
  5. Leverage resulting memory corruption for further exploitation

How to detect it

Search kernel logs for UBSAN array-index-out-of-bounds messages referencing f_uac1_opts_p_srate_store or f_uac2_opts_p_srate_store; monitor configfs write activity to UAC rate attributes for unusually long lists.

  • UBSAN: array-index-out-of-bounds
  • f_uac1_opts_p_srate_store
  • f_uac2_opts_p_srate_store
  • index 10 is out of range for type 'int [10]'
  • __ubsan_handle_out_of_bounds

What your security team should do

  • Prioritize patching any kernel builds that enable USB gadget UAC1 or UAC2 configfs support
  • Audit systems for exposure of configfs USB gadget interfaces to untrusted local users
  • Enable CONFIG_UBSAN_BOUNDS and monitor for related reports in test environments
  • Restrict write access to configfs USB gadget attributes via permissions or SELinux policies

The record

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: uac: validate rate list length before storing UAC1 and UAC2 configfs rate-list attributes parse a comma-separated list of sampling rates and store each parsed value in fixed-size arrays. The arrays have UAC_MAX_RATES entries, but the store paths do not check that the input contains at most that many tokens before writing through opts->name##s[i++]. Writing more than ten rates therefore writes past the end of the p_srates[] or c_srates[] array in struct f_uac1_opts or struct f_uac2_opts. With CONFIG_UBSAN_BOUNDS enabled, writing an 11-entry rate list to the UAC1 p_srate attribute reports: UBSAN: array-index-out-of-bounds drivers/usb/gadget/function/f_uac1.c:1669:1 index 10 is out of range for type 'int [10]' __ubsan_handle_out_of_bounds.cold f_uac1_opts_p_srate_store configfs_write_iter vfs_write ksys_write do_syscall_64 The same reproducer against the UAC2 p_srate attribute reports: UBSAN: array-index-out-of-bounds drivers/usb/gadget/function/f_uac2.c:2087:1 index 10 is out of range for type 'int [10]' __ubsan_handle_out_of_bounds.cold f_uac2_opts_p_srate_store configfs_write_iter vfs_write ksys_write do_syscall_64 Reject additional tokens once UAC_MAX_RATES entries have been parsed. Also keep the original kstrdup() pointer for kfree(), because strsep() advances the parsing cursor. Freeing the advanced cursor leaks the original buffer on successful parses and can free an interior pointer on some error paths.

Affected packages

Ecosystem Package Introduced Fixed