high 7.1

CVE-2026-31778 json

ALSA: caiaq: fix stack out-of-bounds read in init_card

published 2026-05-01 6 mo ago modified 2026-11-06 3 d ago also EUVD-2026-26591

cvss: 7.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.1%; EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits: 0; none known

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

The loop creates a whitespace-stripped copy of the card shortname where `len < sizeof(card->id)` is used for the bounds check. Since sizeof(card->id) is 16 and the local id buffer is also 16 bytes, writing 16 non-space characters fills the entire buffer, overwriting the terminating nullbyte.

When this non-null-terminated string is later passed to snd_card_set_id() -> copy_valid_id_string(), the function scans forward with `while (*nid && ...)` and reads past the end of the stack buffer, reading the contents of the stack.

A USB device with a product name containing many non-ASCII, non-space characters (e.g. multibyte UTF-8) will reliably trigger this as follows:

BUG: KASAN: stack-out-of-bounds in copy_valid_id_string sound/core/init.c:696 [inline] BUG: KASAN: stack-out-of-bounds in snd_card_set_id_no_lock+0x698/0x74c sound/core/init.c:718

The off-by-one has been present since commit bafeee5b1f8d ("ALSA: snd_usb_caiaq: give better shortname") from June 2009 (v2.6.31-rc1), which first introduced this whitespace-stripping loop. The original code never accounted for the null terminator when bounding the copy.

Fix this by changing the loop bound to `sizeof(card->id) - 1`, ensuring at least one byte remains as the null terminator.

Patch / fix

fixed in 1 distros 4 links 8

Linux Linux 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, 6.18.22, 6.19.12, 7.0

debian ubuntu suse opensuse

linux Debian 12 6.1.170-1
linux Debian 13 6.12.85-1
linux Debian 14 6.19.12-1

debian advisories DEBIAN-CVE-2026-31778

linux Ubuntu 22.04 LTS 5.15.0-186.196
linux Ubuntu 24.04 LTS 6.8.0-136.136
linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72
linux-gke Ubuntu 22.04 LTS 5.15.0-1108.114
linux-gke Ubuntu 24.04 LTS 6.8.0-1059.67

ubuntu advisories UBUNTU-CVE-2026-31778

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-source Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
kernel-default Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
kernel-kvmsmall Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-51.1
kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.37.1
kernel-rt Linux Micro 6.2 6.12.0-160000.37.1
kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1

suse advisories SUSE-SU-2026:23244-1 SUSE-SU-2026:23241-1 SUSE-SU-2026:23194-1 SUSE-SU-2026:23193-1 SUSE-SU-2026:23237-1 SUSE-SU-2026:23068-1

kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-31778 updated 2026-11-07 cvss 5.5

kernel: ALSA: caiaq: fix stack out-of-bounds read in init_card

Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
affected: workaround, no fix planned “To mitigate this issue, prevent the snd_usb_caiaq module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.”
Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
affected: workaround, no fix available “To mitigate this issue, prevent the snd_usb_caiaq module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 3 d ago (2026-11-06)

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-125 Out-of-bounds Read

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2026-31778
NVD CVE-2026-31778

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary