CVE-2026-31778: In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: fix stack out-of-bounds read in init_card The loop creates a whites...

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: fix stack out-of-bounds read in init_card 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.

Metrics

CVSS 3.1

7.1/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS Probability

0.13%

2.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-125

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	>= 2.6.31, < 5.10.253	—
Linux	Linux Kernel	>= 5.11, < 5.15.203	—
Linux	Linux Kernel	>= 5.16, < 6.1.168	—
Linux	Linux Kernel	>= 6.2, < 6.6.134	—
Linux	Linux Kernel	>= 6.7, < 6.12.81	—
Linux	Linux Kernel	>= 6.13, < 6.18.22	—
Linux	Linux Kernel	>= 6.19, < 6.19.12	—
Linux	Linux Kernel	7.0	Rc1

References

Timeline

Published: May 1, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-31778?

In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: fix stack out-of-bounds read in init_card 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.

How severe is CVE-2026-31778?

CVE-2026-31778 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.

How do I fix CVE-2026-31778?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.