CVE-2026-93053speakup: keyhelp: guard letter_offsets possible out-of-range indexing

Official description

In the Linux kernel, the following vulnerability has been resolved: speakup: keyhelp: guard letter_offsets possible out-of-range indexing help_init() builds letter_offsets[] by using the first byte of each function name as an index via `(start & 31) - 1`. If function_names are overridden from sysfs (root) with a name starting outside [a–z], the index underflows or exceeds the array, leading to OOB write. Function names can be overridden with the following commands as root: modprobe speakup_soft echo "0 _bad" > /sys/accessibility/speakup/i18n/function_names # then press Insert+2 on /dev/tty This fix checks the first letter in help_init(), and if it is not in the [a–z] range the function returns an error to the caller. Eventually this error is propagated to drivers/accessibility/speakup/main.c:2217, which causes a bleep sound.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/fd339b9ef0accb2c24a5285df842552ebf5eb146
• https://git.kernel.org/stable/c/900cd6e5ef46bd15153762fb26bb03f874fccc52
• https://git.kernel.org/stable/c/6b39969c724d39b6062efa354dc2d38442bfd021
• https://git.kernel.org/stable/c/2e91ab73f9beb659f581e2a6a09f79ace1140905
• https://git.kernel.org/stable/c/d7deb90c4cd086cb111f0ecc9da021218fbde1b0
• https://git.kernel.org/stable/c/5310334762c3f08f51dc2414344dd47492c07d1d
• https://git.kernel.org/stable/c/ca4489b3e54666a7cac7294e71a3cf64e5e95286
• https://git.kernel.org/stable/c/6a19ad4d68c95185308cd9e5d169b10a2cf236c8