What’s Vulnerable › Vulnerabilities

CVE-2026-89726: lib/ucs2_string.c: fix out-of-bounds read in ucs2_strnlen()

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-11 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: lib/ucs2_string.c: fix out-of-bounds read in ucs2_strnlen() Patch series "lib/ucs2_string.c: fix out-of-bounds read in ucs2_strnlen()", v2. This series fixes an off-by-one out-of-bounds read in ucs2_strnlen(). The first patch is the real fix, the second patch comes as a bonus and fixes the code indentation. This patch (of 2): ucs2_strnlen() checks the current character before checking whether the caller-provided maximum length has been reached. If the input is not NUL-terminated within that bound, the loop can read one ucs2_char_t past the limit. Test the length before dereferencing to prevent an off-by-one out-of-bounds read.

Affected products

• Linux kernel: 2.6.12 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/04ae68af4107600120c3c41c94268f43bc350d48
• https://git.kernel.org/stable/c/1b0dc3cbb8630f0b5cb34d848628225920a904be
• https://git.kernel.org/stable/c/2e5a70a175f0c74e7238b013a96c4eabc3002934
• https://git.kernel.org/stable/c/3ada20e110bf3245edb0a3bcddadc33d0f142f8d
• https://git.kernel.org/stable/c/60c74f42f5abddb85dd919b4448d5474e65dbe76
• https://git.kernel.org/stable/c/709eb41adaf78d59d4579a13a898125919b69bcc
• https://git.kernel.org/stable/c/7d658da725ea81c91f73087547b97e7ced82d62b
• https://git.kernel.org/stable/c/cec0d03fe785380540dc1b4d07c80f67ae2ffc78

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