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

Unknown severity · Source severity not reportedCVE-2026-89726

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

Answer in brief

CVE-2026-89726 records a Unknown severity vulnerability in lib/ucs2_string.c: fix out-of-bounds read in ucs2_strnlen(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <709eb41adaf78d59d4579a13a898125919b69bcc \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <7d658da725ea81c91f73087547b97e7ced82d62b \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1b0dc3cbb8630f0b5cb34d848628225920a904be \|\| >=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <cec0d03fe785380540dc1b4d07c80f67ae2ffc78	709eb41adaf78d59d4579a13a898125919b69bcc, 7d658da725ea81c91f73087547b97e7ced82d62b, 1b0dc3cbb8630f0b5cb34d848628225920a904be, cec0d03fe785380540dc1b4d07c80f67ae2ffc78
Linux/Linuxgeneric	2.6.12	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 709eb41adaf78d59d4579a13a898125919b69bcc if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.