How severe is CVE-2026-21523?

CVE-2026-21523 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-21523 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21523?

CVE-2026-21523 affects Microsoft Visual Studio Code. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21523?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-21523 have an EU (EUVD) identifier?

Yes. CVE-2026-21523 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-7345.

When was CVE-2026-21523 published?

CVE-2026-21523 was published on 2026-02-10 and last updated on 2026-06-17.

CVE-2026-21523

CVE-2026-21523 is a high-severity vulnerability in Microsoft Visual Studio Code with a CVSS 3.x base score of 8.0. 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-367.

Key facts

Severity: High (CVSS 3.x base score 8.0)
EPSS exploit prediction: 1% (54th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-7345
Weakness: CWE-367
Affected product: Microsoft Visual Studio Code
Published: 2026-02-10
Last modified: 2026-06-17

Description

Time-of-check time-of-use (toctou) race condition in GitHub Copilot and Visual Studio allows an authorized attacker to execute code over a network.

Frequently asked questions

What is CVE-2026-21523?: Time-of-check time-of-use (toctou) race condition in GitHub Copilot and Visual Studio allows an authorized attacker to execute code over a network.
How severe is CVE-2026-21523?: CVE-2026-21523 has a CVSS 3.x base score of 8.0, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-21523 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (54th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21523?: CVE-2026-21523 affects Microsoft Visual Studio Code. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21523?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-21523 have an EU (EUVD) identifier?: Yes. CVE-2026-21523 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-7345.
When was CVE-2026-21523 published?: CVE-2026-21523 was published on 2026-02-10 and last updated on 2026-06-17.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21523

Affected products (1)

cpe:2.3:a:microsoft:visual_studio_code:*:*:*:*:*:-:*:*

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