RCE in GitHub Copilot and Visual Studio; widely used dev tools; could enable remote compromise across orgs.
CVE-2026-21256
Remote code execution via command injection in GitHub Copilot and Visual Studio.
Is CVE-2026-21256 being exploited?
Not confirmed. CVE-2026-21256 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 1.1% probability of exploitation in the next 30 days.
How severe is CVE-2026-21256?
CVE-2026-21256 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-21256?
Yes. A fix has been recorded for CVE-2026-21256. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-21256 affect?
CVE-2026-21256 affects GitHub Copilot, Visual Studio. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-21256?
Patch when available or upgrade to patched versions
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution over network via command injection; attacker can run arbitrary code on affected systems.
Immediate action required
- affected>= 17.14.0 and < 17.14.26
- affected< 18.3.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.