CVE Intelligence
Unknown

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

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.

Published Sep 11, 2026 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+1

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.18%
ahead of 7% of scored CVEs · Oct 21, 2026
Affects
Linux
Linux
CVSS base
—
Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 04ae68af4107600120c3c41c94268f43bc350d48≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 2e5a70a175f0c74e7238b013a96c4eabc3002934≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 3ada20e110bf3245edb0a3bcddadc33d0f142f8d≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 60c74f42f5abddb85dd919b4448d5474e65dbe76≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 709eb41adaf78d59d4579a13a898125919b69bcc≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 7d658da725ea81c91f73087547b97e7ced82d62b≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < 1b0dc3cbb8630f0b5cb34d848628225920a904be≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and < cec0d03fe785380540dc1b4d07c80f67ae2ffc78
and 1 more version 2.6.12
Vulnerable CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 21, 2026 · 6 reading(s) · max 0.18%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Not enough vector or weakness data: use the affected application’s logs as a starting point.
application logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Record published
    Oct 15, 2026
  • Affected products added · linux/linux
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Received
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 11, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× References added · Oct 19, 2026 – Oct 19, 2026
  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

10 on the record

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

  • CVE-2026-98869 bpf: Infer zext_dst based on static register liveness analysis 17h
  • CVE-2023-7356 Bluetooth: ISO: Copy BASE if service data matches EIR_BAA_SERVICE_UUID 17h
  • CVE-2026-98866 sched/cache: Introduce task_struct->sched_cache_grp to fix UAF 3d
  • CVE-2026-98867 dm-pcache: bound the logical key offset from persistent memory 3d
  • CVE-2026-98868 dm-pcache: reject a kset that overruns its segment 3d
  • CVE-2026-98856 kprobes: Skip disarmed probes when checking optkprobe overlap 3d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CVSS score published by NVD, the CNA, CISA or GitHub so far.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No CWE classification.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-89726 is "lib/ucs2_string.c: fix out-of-bounds read in ucs2_strnlen()", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.18% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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