How severe is CVE-2026-45455?

CVE-2026-45455 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-45455 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-45455?

CVE-2026-45455 primarily affects Microsoft 365 Apps. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-45455?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-45455 have an EU (EUVD) identifier?

Yes. CVE-2026-45455 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35539.

When was CVE-2026-45455 published?

CVE-2026-45455 was published on 2026-06-09 and last updated on 2026-06-19.

CVE-2026-45455

CVE-2026-45455 is a low-severity vulnerability in Microsoft 365 Apps with a CVSS 3.x base score of 3.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: Low (CVSS 3.x base score 3.3)
EPSS exploit prediction: 1% (46th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-35539
Weakness: CWE-125
Affected product: Microsoft 365 Apps
Published: 2026-06-09
Last modified: 2026-06-19

Description

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.

Frequently asked questions

What is CVE-2026-45455?: Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
How severe is CVE-2026-45455?: CVE-2026-45455 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-45455 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (46th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-45455?: CVE-2026-45455 primarily affects Microsoft 365 Apps. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-45455?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-45455 have an EU (EUVD) identifier?: Yes. CVE-2026-45455 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-35539.
When was CVE-2026-45455 published?: CVE-2026-45455 was published on 2026-06-09 and last updated on 2026-06-19.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45455

Affected products (14)

cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:excel:2016:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:microsoft_365:-:*:*:*:*:macos:*:*
cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x64:*
cpe:2.3:a:microsoft:office_2019:-:*:*:*:*:*:x86:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x64:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:-:x86:*
cpe:2.3:a:microsoft:office_2021:-:*:*:*:ltsc:macos:-:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x64:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:-:x86:*
cpe:2.3:a:microsoft:office_2024:-:*:*:*:ltsc:macos:-:*
cpe:2.3:a:microsoft:office_online_server:-:*:*:*:*:*:*:*

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