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NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Fixed version: Linux Linux 04ae68af4107600120c3c41c94268f43bc350d48, 1b0dc3cbb8630f0b5cb34d848628225920a904be, 2e5a70a175f0c74e7238b013a96c4eabc3002934; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 04ae68af4107600120c3c41c94268f43bc350d48, 1b0dc3cbb8630f0b5cb34d848628225920a904be, 2e5a70a175f0c74e7238b013a96c4eabc3002934; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 6.6.157.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Sep 11, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 7th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 04ae68af4107600120c3c41c94268f43bc350d48affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 2e5a70a175f0c74e7238b013a96c4eabc3002934affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 3ada20e110bf3245edb0a3bcddadc33d0f142f8daffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 60c74f42f5abddb85dd919b4448d5474e65dbe76affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 709eb41adaf78d59d4579a13a898125919b69bccaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 7d658da725ea81c91f73087547b97e7ced82d62baffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 1b0dc3cbb8630f0b5cb34d848628225920a904beaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before cec0d03fe785380540dc1b4d07c80f67ae2ffc78affected · git
    • before 2.6.12not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-89724Sep 11, 2026 · media: vicodec: fix out-of-bounds write in FWHT encoder
    31Monitor
  • ← EarlierCVE-2026-89725Sep 11, 2026 · media: cec: stm32: prevent out-of-bounds write on RX overflow
    35Monitor
  • Later →CVE-2026-89727Sep 11, 2026 · KVM: arm64: GICv2: Don't WARN on out-of-range GICV_DIR INTID
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux04ae68af4107600120c3c41c94268f43bc350d48Vendor (CNA)
Linux Linux1b0dc3cbb8630f0b5cb34d848628225920a904beVendor (CNA)
Linux Linux2e5a70a175f0c74e7238b013a96c4eabc3002934Vendor (CNA)
Linux Linux3ada20e110bf3245edb0a3bcddadc33d0f142f8dVendor (CNA)
Linux Linux60c74f42f5abddb85dd919b4448d5474e65dbe76Vendor (CNA)
Linux Linux709eb41adaf78d59d4579a13a898125919b69bccVendor (CNA)
Linux Linux7d658da725ea81c91f73087547b97e7ced82d62bVendor (CNA)
Linux Linuxcec0d03fe785380540dc1b4d07c80f67ae2ffc78Vendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records