Homepage

CVE-2026-63949 Affecting kernel-kvmsmall package, versions <6.12.0-160000.37.1

Severity

 Recommended
0.0
low
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.22% (12th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-SLES1600-KERNELKVMSMALL-19334059
  • published27 Aug 2026
  • disclosed11 Aug 2026
Report a new vulnerability Found a mistake?

Introduced: 11 Aug 2026

NewCVE-2026-63949  (opens in a new tab)

How to fix?

Upgrade SLES:16.0.0 kernel-kvmsmall to version 6.12.0-160000.37.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-kvmsmall package and not the kernel-kvmsmall package as distributed by SLES. See How to fix? for SLES:16.0.0 relevant fixed versions and status.

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

auxdisplay: line-display: fix OOB read on zero-length message_store()

linedisp_display() unconditionally reads msg[count - 1] before checking whether count is zero, so a write of zero bytes to the message sysfs attribute hits msg[-1]:

write(fd, &#34;&#34;, 0);


-&gt; message_store(..., buf, count=0)
   -&gt; linedisp_display(linedisp, buf, count=0)
      -&gt; msg[count - 1] == &#39;\n&#39;  ; OOB read

The kernfs write buffer for that store is a 1-byte allocation (kernfs_fop_write_iter() does kmalloc(len + 1) with len == 0), so msg[-1] is a 1-byte read before the slab object. On a KASAN-enabled kernel this trips an out-of-bounds report and panics; on stock kernels it silently reads adjacent slab data and, if that byte happens to be '\n', the following count-- wraps ssize_t 0 to -1 and is then passed to kmemdup_nul().

linedisp_display() is reached from the message_store() sysfs callback (drivers/auxdisplay/line-display.c message attribute, mode 0644) and from the in-tree initial-message setup with count == -1, so the OOB path is only userspace-triggerable via zero-byte writes; vfs_write() does not short-circuit on count == 0 and kernfs_fop_write_iter() dispatches the store callback regardless.

Guard the trailing-newline trim with a count check. The existing if (!count) block then takes the clear-display path unchanged.

Affects every auxdisplay driver that registers via linedisp_register() / linedisp_attach(): ht16k33, max6959, img-ascii-lcd, seg-led-gpio.

CVSS Base Scores

version 3.1