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CVE-2026-93122
usb: gadget: uac: validate rate list length before storing
Published 2026-09-17 (31 days ago) by the Linux kernel CNA. Subsystem drivers/usb. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-93122 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/usb/gadget/function/f_uac1.c
drivers/usb/gadget/function/f_uac2.c
- What this is
- USB SUBSYSTEMMAINTAINERS section matched on drivers/usb/ · linux-usb@vger.kernel.org · Supported
- Kernel module
- usb_f_uac1
Check it on the machine
grep -wE 'CONFIG_OF|CONFIG_PCI|CONFIG_USB|CONFIG_USB_F_UAC1|CONFIG_USB_GADGET|CONFIG_USB_PHY|CONFIG_USB_SUPPORT' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w usb_f_uac1Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.
- bookwormMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
- trixieMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt/amd64, arm64/cloud-arm64, armel/rpi, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- forky, sidMnot built on amd64/amd64, amd64/cloud-amd64, amd64/rt-amd64, arm64/cloud-arm64, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_OF, CONFIG_PCI, CONFIG_USB, CONFIG_USB_F_UAC1, CONFIG_USB_GADGET, CONFIG_USB_PHY, CONFIG_USB_SUPPORT
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-09-17 (31 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 6.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/usb
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.18 | 6.18.57 | 0203146ad450 |
| 5.18 | 7.2.6 | 3819c6f255a3 |
| 5.18 | 7.3 | 844d83d5964b |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The malformed comma-separated rates enter via write(2)→configfs_write_iter()→f_uac1_opts_p_srate_store/f_uac1_opts_c_srate_store (and the UAC2 twins) on /sys/kernel/config/usb_gadget/<g>/functions/uac{1,2}.*/{p,c}_srate; USB SETUP/iso packets never supply that page.
- AC:LAttack complexity, low
- A fresh function_make() uac1/uac2 instance has opts->refcnt==0, so one write of eleven or more kstrtou32 tokens (up to configfs SIMPLE_ATTR_SIZE-1 bytes) stores through opts->p_srates[i++]/c_srates[i++] past UAC_MAX_RATES with no race or victim state.
- PR:LPrivileges required, low
- f_uac1_opts_p_srate_store and f_uac2_opts_p_srate_store (and the c_srate stores) do no capable() check; CONFIGFS_ATTR is S_IWUSR, and Android/embedded USB gadget HALs routinely chown /sys/kernel/config/usb_gadget to a non-root system or HAL daemon.
- UI:NUser interaction, none
- The attacker mkdir's the uac1/uac2 function instance and writes the oversized p_srate or c_srate list themselves; no other user must plug a cable, mount a volume, or open a file.
- S:UScope, unchanged
- The store overwrites the kmalloc'd struct f_uac1_opts/f_uac2_opts and neighbouring host-kernel slab in the same OS authority; it is not a VM escape, IOMMU/DMA bypass, or sandbox breakout.
- C:HConfidentiality impact, high
- Each extra token is an attacker-chosen u32 written past p_srates[9]/c_srates[9] into the rest of the kzalloc'd opts object and adjacent slab; that heap overflow is groomable into a kernel-memory disclosure primitive.
- I:HIntegrity impact, high
- f_uac1_opts_p_srate_store writes attacker-controlled ints past p_srates[] over p_ssize, the 126-byte name arrays, refcnt, and opts->lock, then mutex_unlock()s the corrupted mutex — an arbitrary-write and control-flow hijack primitive.
- A:HAvailability impact, high
- The commit's UBSAN report is array-index-out-of-bounds at f_uac1_opts_p_srate_store/f_uac2_opts_p_srate_store index 10 of int[10]; without UBSAN the same store corrupts opts->lock and adjacent slab and oopses or panics.